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## Scatter palindrome hackerrank

def Dec 10, 2019 · Palindrome Index hackerrank solution: In this video, I have solved hackerrank Palindrome Index problem in an easy way. ie Hacker Rank solution for 30 Days Of Code, HackerRank Algorithms. For the third case, there are 3 possible swaps. * A palindrome is a string which reads the same forward and backwards. The idea is for each character in the given input string, we consider it as midpoint of a palindrome and expand it in both directions to find all palindromes of even and odd lengths. com/ web. . If you need a break from formal writing activities this week, gather the family together for some fun with palindromes! A palindrome is any word or phrase that reads the same either forward or backward. /*. It should return a string representing the largest value palindrome achievable, or -1. An integer is a palindrome when it reads the same backward as forward. A Palindromic number or numeral Palindrome is a number, which remains the same when its digits are reversed. Code Golf Stack Exchange is a site for recreational programming competitions, not general programming questions. like consider 10 floors ,3 lifts 1st lift in 1st flloor 2nd lift is in 10 3rd 故紙堆裏寄此生 後之覽者，亦將有感於斯文。 Feb 17, 2011 · Last Thursday night at Oredev, after the sessions, was "Birds of a Feather" - a sort of mini-unconference. If we use brute-force and check whether for every start and end position a substring is a palindrome we have O(n^2) start - end public class Palindrome { /* Declare a node of the linked list containing the stack */ class Node { /* Instance variables for the Node class */ char data;: Node next; /* Constructor for the Node Class */ Solution to problems from HackerRank. Therefore I process the string as in a normal palindrome check, if it fails I try to figure out if the removal of the left index helps or not. It's 999999 for the original problem. special palindrome strings {a,b,c,b,a,b,a,bcb,bab,aba} but in above example my program is finding abcba as palindrome also this leads to failure of test cases Solve the Palindromic String practice problem in Basic Programming on HackerEarth and improve your programming skills in Input/Output - Basics of Input/Output. Input: abckdeedcba Output: 3 (0 based indexing) To start off with the problem, we must first understand that there can be two possible ways to make the string a palindrome. Find and return the shortest palindrome you can find by performing this transformation. You can find HackerRank C++ (CPP) solution, and also practice and submit all HackerRank problems solution in one place. Please try again later. We can solve this problem in O(n 2) time and O(1) space. Two cells are said to be connected if they are adjacent to each other horizontally, vertically, or diagonally; in other words, cell is connected to cells , , , , , , and , provided that the location exists in the matrix for that . Also insert all the individual characters from the string into the HashMap (to generate distinct single letter palindromic sub-strings). com. This hackerrank problem is a part of P Short Palindrome - HackerRank - world codesprint #5 July 25, 2016 Problem statement Julia spent 3+ hours to score 13 out of 40 points, she enjoyed the time to work on A simple solution would be to generate all substrings of the given string and print substrings that are palindrome. The complexity of For every string given as input, you need to tell us the number of subsequences of it that are palindromes (need not necessarily be distinct). Thank you! Here is my code: # Complete the palindromeIndex function below. 7 abcbaba. h> #include <stdbool. We want to rearrange letters of the given string baseString so that it becomes a palindrome. Length of palindrome substring is greater then or equal to 2. Since Published At 03 02 2019 - 16:26:23 This Video has been viewed by [VIEW] viewers, Among them there are [LIKED] Likes and [DISLIKED]dislikes. Time complexity of this step is O(n^3) assuming that the hash insert search takes O(1) time. k: an integer that represents the maximum number of changes allowed. What is the expected number of swaps you will make? Madam Hannah Otto, the CEO of Reviver Corp. You have to find two palindrome which are non-overlapping subsequences such that the product of their lengths is maximised. com/challenges/palindrome-index. solution, hackerrank day 0 solution in c, write a line of code here that prints the contents of inputstring to stdout. The logic to Mini-Max Sum Hackerrank Solution in C++ The First step is to take an input from the user and after that take another variable to add all 5 number of an array and store the sum of 5 variable in sum name variable for better understanding let's take an example to suppose array 5 elements are 2, 5, 1, 4, 3. This mainly involves three steps. The substrings with different start indexes or end indexes   2 Apr 2019 A palindrome is a word that is spelled the same backward and forward, for variable-length argument arrays, the gather and scatter operators. And if the input number is “9 9 9”, the output should be “1 0 0 1”. bem2ng · bemhint · bemlint · bemowo-bike-bikes · bemu-cli · bemuse-tools · ben-canvas-game · ben-fork-react-scripts · ben-palindrome · ben-react-dev-utils  HarckerRank, etc. A palindromic border is a border that is palindromic. , hackerrank hello world solution, Day 18: Queues and Stacks hackerrank, print hello, world. Constraints. (Furthermore, the letter l is also common, but you only need to find one common substring. For our immediate purpose, a palindrome is a sequence of decimal numbers that when read forward or backwards contains the same digits. yinwang. Now you can remove the characters individually to check if string becomes palindrome, or simply observe that the characters after 'a' match with the corresponding characters starting back from 'b' on the other side, i. rozick1. special palindrome strings {a,s,a,s,d,asa,sas} Input. reg 15:47 keyboard http://www. It gets shared to your followers' Disqus feeds, and gives the creator kudos! Start the discussion… ⬇ Drag and drop your images here to upload them. A few single-word examples are bib, civic, radar, level, and mom. of a positive integer. Discussion Recommended! Recommending means this is a discussion worth sharing. Liked by Generated the Scatter Plot, Pearson's Correlation, and R-square values to check the weak and strong may include maxSearch, mergeSort, BubbleSort, factorial, armstrong, palindrome, etc. Note that the empty string is not a palindrome. ) put a string in a DLL and check for Pallindrome 2. Feb 11, 2015 · This feature is not available right now. ) Short Problem Definition: Louise and Richard play a game. find the number of occurence of words in a given senetence eg: input:an apple in an apple output: an-2 apple-2 in-1 17. Mar 25, 2019 · If the first line of a query contains the String Insert, then the second line contains two space separated integers , and the value must be inserted into at index . Your task is to figure out the index of the character on whose removal it will make the string a palindrome. on the first line and the contents of input Jan 11, 2017 · Equalize the Array HackerRank solution in c. If a string has the first and last letters the same, and the remaining letters (I think it's a [1: -1] slice in Python, but my Python is a bit rusty) are a palindrome, it's a palindrome. A simple solution would be to generate all substrings of the given string and print substrings that are palindrome. An example for this could be: (word[0] == word[word. ",hackerrank 30 days of code solutions in c, day 0 hello world. Check whether substring(i,j) is a palindrome Don't do it. ted. , is fond of palindromes, or words that read the same forwards or backwards. The idea is inspired from Longest Palindromic Substring problem. com/how Beautiful strings solution Jun 08, 2017 · Hackerrank - Problem description. find the number of occurence of words in a given senetence eg: input:an apple in an apple output: an-2 apple-2 in-1 in the evening session real time application problems -lift scenario. It's easy to see that the expected number of swaps needed is 3. Hua Hua 2,930 views. html https://ideas. Hopefully it will be done in an hour or so. Print "Palindrome" if String is Palindrome else Print"Not Palindrome"(Without Quotes). Find the largest palindrome made from the product of two 3-digit numbers. If you didn't know what a palindrome was, hopefully you looked it up. hackerrank. e. Product LeetCode – Shortest Palindrome (Java) Given a string S, you are allowed to convert it to a palindrome by adding characters in front of it. January 11, 2017 . Aug 29, 2015 · Due to the problem specification there exists only one valid solution (and it always exists). Length of palindrome sub string is greater than or equal to 2. 2 Answers; Went for a backend role,  Problem Statement: Given a string, your task is to count how many palindromic substrings in this string. Since assemblers get stuck at these chimeric reads, the palindrome pattern in We study the input contigs C1 produced by Spades using a scatter plot in Fig . Anyone could write up a topic on Feb 17, 2011 · Data structures, Algorithms, Coding, Technical Interview Questions and much more. Louise gets the first turn and the turns alternate thereafter. Oct 15, 2017 · Idea is to use DP. Onsite with three 45 minute technical Coding question online regarding palindromes (easy). The term palindromic is derived from Palindrome, which refers to a word (such as rotor or racecar) whose spelling is unchanged when its letters are reversed. In the game, they perform the following operations. This simply changes the central condition to $$r . ' ***Solution to Day 19 skipped, because Pyhton implementation was not available at the time of completion. com/. for hepatocyte growth factor and is involved in cell proliferation, scattering, narrative: The POU dimer from the OCT-1 gene formed on the palindromic OCT. If The Given String is Palindrome Then Print "Palindrome" (Without Quotes) else Print "Not Palindrome" (Without Quotes) Input Format. Example 1: Input: 121 Output: true . A simple speedup is achieved by observing that at least one divisor i must be i>=100 and i^2<=palindrome. Given a String S, Check Whether The Given String S is Palindrome or Not. Concerning the cost optimization, you're making at least two mistakes. Given a string of lowercase letters in the range ascii[a-z], determine a character that can be removed to make the string a palindrome. tw/~u91029/AlgorithmAnalysis. Then, do a brute-force recursively passing in the candidates that are palindrome. You need to check whether it's a palindrome or not. C# Palindrome Method: Words and Sentences Develop an algorithm that determines if a string is a palindrome. So, his friend advised him to type the sentence "The quick brown fox jumps over the lazy dog" repeatedly, because it is a pangram. The core of this question is determining whether or not an input string is a palindrome in its current orientation or determining the index of a character that could be removed to make the input string a palindrome. 5. For example “racecar” is a palindrom This is the solution for the problem Matrix Rotation in Python, found in the algorithm domain of Hackerrank. There may be more than one solution, but any will do. Therefore it is not a palindrome. and start a loop for gap > 2 and find if chars are equal and in that gap and check if inner substring within this gap is also palindrome by checking value in DP , if so then increment count by 1 and both neighbor substring and exclude common substring. The Next Palindrome Problem code: PALIN A positive integer is called a palindrome if its representation in the decimal system is the same when read from left to right and from right to left. Contribute to settyblue/HackerRank development by creating an account on GitHub. Output Format. For example, a and ana are palindromic borders of anabanana, l, lol and lolol are palindromic borders of lololol. For every string given as input, you need to tell us the number of subsequences of it that are palindromes (need not necessarily be distinct). Note. hackerrank sparse arrays problem can be solved by using map data structure. n: an integer that represents the length of the integer string. nearest perfevt square of a number . Hacker Rank Solution Program In C++ For " Day 0: Hello, World. palindrome of strings, transpose of matrix. She thinks palindromic brand Find the number of non-empty subsets of characters, where , such that characters can be rearranged to form a palindrome. 3. May 02, 2018 · Write a program to check for string is palindrome or not using stack and queue. * If it is allowed to make $x \rightarrow y$, then it is allowed to make $y \rightarrow x$ * If it is allowed to make $x \rightarrow y$ Given a String S, Check Whether The Given String S is Palindrome or Not. HackerRank: Short Palindrome (in Algorithm) Problem Statement Consider a string, , of lowercase English letters where each character, , denotes the letter at index in . Given a number, find the next smallest palindrome larger than this number. org/blog-cn/2017/10/16/ergonomics P NP NPC http://www. I 0 votes and 0 comments so far on Reddit HackerRank Solution in CPP domain. Length-1-0]) would compare the first letter with the last letter of word, and (word[1] == word[word. does not contain the last four characters of hackerrank, so we print NO on a new line. Check out the Tutorial tab for learning materials and an instructional video! A palindrome is a word, phrase, number, or other sequence of characters which reads the same backwards and forwards. I create six-digit palindromes by splitting a three-digit numbers into its single digits. n-1 (1) Assume position i is the center of a palindrome (2) Move left and right from i while (1) is true Jun 07, 2016 · Posts about HackerRank written by jtalics. Create a function to check whether a string is a palindrome. Previous: Write a program in C to display the number in reverse order. Idea is to get an alphanumeric string with all lower case and check for palindrome. The string will become "bab","bba" or remain "abb" with 1/3rd probability each. Modifications by HackerRank. For input baa, removing b from the string makes the string palindrome, hence the position 0. Medium. There is a better O(n^2) solution, which is the one I'll implement in this post: For i 0. Education. You will be given a String baseString. Jun 29, 2018 · > You are given a string $S$ and a set of allowed transformations. Count All Palindrome Sub-Strings in a String | Set 2 Given a string, the task is to count all palindrome substring in a given string. hackerrank, print hello, world. end to iterate for data with local partitions only, need to do scatter\gather\rank during query longest palindromic substring,; Fenwick Tree (Binary indexed tree)– common use полагаться на автоматизированные тесты на https://hackerrank. Now he can exchange 2 of the 3 wrappers and get 1 additional piece of chocolate. 0000 Find the number of non-empty subsets of characters, where , such that characters can be rearranged to form a palindrome. Palindromic Substrings. SAMPLE INPUT Hacker Rank Solution Program In C++ For " Day 18: Queues and Stacks ",hackerrank 30 days of code solutions in c, Day 18: Queues and Stacks solution, hackerrank day 0 solution in c, write a line of code here that prints the contents of inputstring to stdout. Example 2: Input: -121 Output: false Explanation: From left to right, it reads -121. Easy HackerRank challenge. length() compared to C (which is called B in the linked challenge). HackerEarth is the largest network of top developers around the globe, helping them connect with other developers and discover the best job opportunities. Feb 02, 2020 · scatter palindrome hackerrank solution, palindrome in java, palindrome in c, palindrome in javascript, palindrome in dna, palindrome in php, palindrome in maths, palindrome in dna sequence, I am solving a palindrome index problem from HackerRank as explained below. ) Feb 03, 2014 · WORDPLAY and word games can reenergize kids who feel bogged down with school work. 8:13. Example: abcdedcba is a palindrome with center e, radius 4: but e, ded, cdedc, bcdedcb, and abcdedcba are all palindromes. Link is here: https: //www. Two palindromic subsets are considered to be different if their component characters came from different indices in the original string. Sep 24, 2016 · We were unable to load Disqus. (Subsequence: It is a string derived from deleting some elements without altering order. Aug 15, 2017 · Consider a matrix with rows and columns, where each cell contains either a or a and any cell containing a is called a filled cell. Solution. We need to find out if the product of two 3-figured number is a palindrome and it is smaller than exercise upper constraint. //Problem: https://www. You are given a string S. -If you don't get an inequality condition, the string is palindrome then. My solution starts with initializing two numbers as 999. You randomly swap two characters in a string until the string becomes a palindrome. Count All Palindrome Sub-Strings in a String | Set 1. HackerRank: Palindrome Index To read the full prompt, navigate to HackerRank Palindrome Index Question . If you are just comparing small strings all the time then this is fine, but if you want to defend I currently have the following implementation that handles finding the shortest palindrome with a given string by inserting the minimum number of characters, but only handling character insertions at the front to create the shortest palindrome. METHOD 1 (Use a Stack) A simple solution is to use a stack of list nodes. A palindromic number reads the same both ways. where , , are coordinates on -axis. , bcdcb is palindrome. Hi all I'm doing the Richie Rich hackerrank problem. Next: Write a program in C to find the number and sum of all integer between 100 and 200 which are divisible by 9. com, Scatter Plot . The largest palindrome made from the product of two 2-digit numbers is 9009 = 91 × 99. It states that from a string s find the shortest palindrome by adding some characters to the front of s . cs Feb 02, 2020 · scatter palindrome hackerrank solution, palindrome in java, palindrome in c, palindrome in javascript, palindrome in dna, palindrome in php, palindrome in maths, palindrome in dna sequence, HackerRank - build a palindrome - world code sprint #5 - study Java code - buildaPalindrome1. For example, if lololol, then . In this challenge, Hannah provides a string consisting of lowercase English letters. Short Problem Definition: Louise and Richard play a game. like consider 10 floors ,3 lifts 1st lift in 1st flloor 2nd lift is in 10 3rd 故紙堆裏寄此生 後之覽者，亦將有感於斯文。 gwary jezyka polskiego, Zaczynając od tego, że język polski w Czechach to Zaolzie z Trzyńcem, Karwiną, Hawirzowem gdzie z tej mapy wynika, że sięga aż po Vsetin, Nowy Jiczyn czy Frydek-Mistek. https://www. Let's define as the number of palindromic borders of string . may be taken as Program to plot graphs -scatter plot, box plot and bar plot. Nov 19, 2015 · For input aaab, we can see that removing b from the string makes the string a palindrome, hence the position 3. Hackerrank's problem asks for a variable maximum upper limit. For example, 349 + 943 = 1292, 1292 + 2921 = 4213 4213 + 3124 = 7337 That is, 349 took three iterations to arrive at a palindrome. Cheers, ACC. I think I can solve this by looping through the half the word and comparing each letter with the other half. Output: e l g o oo goog. h> int main(){ int n,temp,count; Given a singly linked list of characters, write a function that returns true if the given list is a palindrome, else false. Participate in programming challenges, and coding competitions on HackerEarth, improve programming skills and get developer jobs. * * You are required to form a palindrome by adding 0 or more characters to the string at * any location which you find appropriate. h> #include <assert. If we reverse a palindrome number, the reversed number would be the same as the original one. Every day, for days, she would select two integers and , take the substring (the substring of from index to index ), and ask the following question: Consider all the palindromes that can be constructed from some of the letters from . The results - If This is Problem 4, finding the largest palindrome product. It will call itself. #hackerrank #reactdeveloper #reactjs. csie. ntnu. The problem description - Hackerrank. Examples: Input : str = "abaab" Output: 3 Explanation : All palindrome substring are : "aba" , "aa" , " 10 Dec 2019 Palindrome Index hackerrank solution: In this video, I have solved hackerrank Palindrome Index problem in an easy way. Length If a string is zero or one letters long, it's a palindrome. Not the complete and exact solution but discussion forum may be helpful for you, sometime even code are given with explained logic. Return the palindrome that can be made from baseString. Initial Thoughts: We can use pointers from the beggining and. Jun 07, 2016 · Posts about HackerRank Solutions written by jtalics. For a given positive integer K of not more than 1000000 digits, write the value of the smallest palindrome larger than K to output. Print "YES" (without quotes) if S is a palindrome and "NO" (without quotes) if S is not a palindrome. First of all, your palindrome function uses inefficient logic. Palindrome :- A palindrome is a word, phrase, number, or other sequence of characters which reads the same backward as forward, such as madam or racecar. This way you have to check 1000 instead of 1000000 numbers. //Java 8. h> #include <stdio. Suppose it is by 1 on x-axis. Write a program to find Pangrams. Because the string contains all the characters in hackerrank in the same exact order as they appear in hackerrank, we print YES on a new line. May 22, 2012 · The main problem is if it's ticking over for any length of time it starts chucking a load of white smoke out of the exhaust and there is a really strong smell coul Palindrome :- A palindrome is a word, phrase, number, or other sequence of characters which reads the same backward as forward, such as madam or racecar. Then print this number modulo on a new line. You are given a 2D matrix, A, of dimension MxN and a positive integer R. The solution discussed here is extension of Longest Palindromic Substring problem. take 2 hex no as a string and add Hackerrank - Problem Statement A description of the problem can be found on Hackerrank. Note that there can be at most O(n^2) palindrome sub-strings of a string. Available at https: Designer PDF Viewer HackerRank solution in c. Return the minimum number of characters which Yesterday I worked on the Highest Value Palindrome challenge at HackerRank. Then print this number modulo on a Step 1: Finding all palindromes using modified Manacher's algorithm: Considering each character as a pivot, expand on both sides to find the length of both even Length of palindrome sub string is greater than or equal to 2. General. Recursive function to check if a string is palindrome; Minimum number of Appends needed to make a string palindrome; Longest Non-palindromic substring; Minimum number of deletions to make a string palindrome; Minimum steps to delete a string after repeated deletion of palindrome substrings; Count of Palindromic substrings in an Index range Dismiss Join GitHub today. If it helps the left index is the answer, if it does not, the right index is the answer. improve this answer. Loop over a string in both directions. Comparing a string to its reverse takes some additional steps, though typically not that many for ordinary strings, near N / 2 steps for almost-palindromes, N steps for palindromes, but that's not a real concern. Like 16461, for example, it is “symmetrical”. (Wikipedia) Palindrome number reads the same from both directions, forward and backward. My program is fed a list of commands, such as: 12 insert 0 5 insert 1 10 insert 0 6 print remove 6 append 9 append 1 sort print pop reverse pri Jul 12, 2017 · Problem: "ad A Man, A plan, a canal: Panama ad" is a palindrome. Take String Input S. For the 1 st test case, the letter o is common between both strings, hence the answer YES. Sentence-length palindromes may be written when allowances are made for adjustments to capital letters, punctuation, and word dividers, such as "A man, a plan, a canal, Panama!", "Was it a car Nov 30, 2016 · by blondiebytes Welcome to Day 18! Today we're learning about Stacks and Queues. n-1 (1) Assume position i is the center of a palindrome (2) Move left and right from i while (1) is true Since the author wants all the solutions, chances are DP won't work here and a brute-force seems to be a better choice. But, to lock the door he needs a key that is an anagram of a certain palindrome string. Challenges must have an objective scoring criterion, and it is highly recommended to first post proposed challenges in the Sandbox. Oct 18, 2015 · This article looks at the interview question - Determine if a string is a palindrome (text that is spelled the same when reversed). Alter the string, one digit at a time, to create the string representation of the largest number possible given the limit to the number of changes. Analysis This problem can be trivially solved by looping through each character and checking it against the character on the opposite side. 24. Recommended: Please solve it on “ PRACTICE ” first, before moving on to the solution. They have a counter set to N. convert that string to an integer x and test with isPalindrome(num2str(x, 2)) whether x 's binary representation is a palindrome, too. If the given string is “bcbc”. In case the string is already a palindrome, then -1 is also… Dismiss Join GitHub today. Code HS Tracy Python Answers Ex . As you already know that this site does not contain only Questions. Example 3: Apr 29, 2017 · The characters of hackerrank are bolded in the string above. The only exception is a string of an odd length ('aba') that has exactly one odd letter count. It's where a word is spelled the same www. Monthly contests hosted in CodeChef / HackerRank, etc,. Web Links: 1. This hackerrank Given a string, your task is to count how many palindromic substrings in this string. A palindrome is a word, phrase, number, or other sequence of characters which reads the same backwards and forwards. Jun 05, 2015 · Shortest Palindrome and KMP algorithm: A little thought! In leetcode, Shortest Palindrome is one of the site's interesting algorithmic problems. edu. The substrings with different start indexes or end indexes are counted as Input: str = google. For each character in the given string, we consider it as mid point of a palindrome and expand in both directions to find all palindromes that have it as mid-point. 188 videos Play all LeetCode Solutions Nick White; LeetCode 238. Jul 30, 2017 · If the string cannot be converted to palindrome or is already a palindrome just return -1. ; If the first line of a query contains the String Delete, then the second line contains index , whose element must be deleted from . Not all numbers produce palindromes so quickly. Microsoft Word - palindromes Author: Caroline Created Date: 1/10/2012 1:38:26 PM the nearest perfevt square of a number . The complexity of this solution would be O(n 3). highestValuePalindrome has the following parameter(s): s: a string representation of an integer. SAMPLE INPUT Apr 25, 2016 · Ice Cream Parlor HackerRank solution | Two Sum LeetCode Solution - Duration: 14:48. Hackerank palindrome problem. Reversing a string takes N steps, where N is the length of the string. java Apr 08, 2016 · hackerrank-Palindrome Index C++ yaffykoyo Ongoing Learning Process , Uncategorized April 8, 2016 June 12, 2016 1 Minute Given a string, , of lowercase letters, determine the index of the character whose removal will make a palindrome. First mark all single length and length two substring of same char TRUE. 0 hackerrank solutions github | hackerrank all solutions | hackerrank solutions for java | hackerrank video tutorial | hackerrank cracking the coding interview solutions | hackerrank data structures | hackerrank solutions algorithms | hackerrank challenge | hackerrank coding challenge | hackerrank algorithms solutions github| hackerrank problem solving | hackerrank programs solutions | JAVAAID Dec 22, 2015 · Algorithm Strings Challenges - Palindrome Index Solution Problem Statement You are given a string of lower case letters. It performs an expensive action on a string, then checks character by character until the strings are not equal and only then returns false if it is not a palindrome. 2) Write a C program to check whether given number is palindrome or not. How would you facet the data using ggplot2 package? Let's take an example to understand faceting 16 May 2019 A DNA palindrome is read similarly when reading it on the direct strand In contrast, genomic islands and ICEs were scattered in the tree. 3 Dec 2019 scatter-R Interview Questions-Edureka. Sentence-length palindromes may be written when allowances are made for adjustments to capital letters, punctuation, and word dividers, such as "A man, a plan, a canal, Panama!", "Was it a car I completed the following exercise on HackerRank. You have to rotate the matrix R times and print the resultant matrix. If the string cannot be converted to palindrome or is already a palindrome just return -1. There will always be a valid solution. You are provided * a function shortPalin which accepts a string S. For example we actually had the palindrome a#b#c#d#e#d#c#b#a , so our length is twice as big. Here we’ll see how to write a C program to check whether a number is a palindrome. I continually decremented second number by 1, until it is equal to 100. As the string aaa is already a palindrome, you can output 0, 1 or 2 as removal of any of the characters still maintains the palindrome Given a string, find all possible palindromic substrings in it. Determine whether an integer is a palindrome. Jul 05, 2016 · shortest palindrome solution find shortest palindrome in a string java example program Java Program to find shortest palindrome in string - InstanceOfJava This is the java programming blog on "OOPS Concepts" , servlets jsp freshers and 1, 2,3 years expirieance java interview questions on java with explanation for interview examination . h> #include <stdlib. The problem with the reverse approach is that it does all the work up front. Jan 16, 2017 · instead of defining the value of 'a' you could use cout<<UINT_MAX-b; //UINT_MAX is the max value of unsigned int and it is defined in limits header file A palindrome is a word or phrase that is the same if read forward or backward. Build a Palindrome HackerRank - challenging-palindromes For the hackerrank implementation, a parameter \(N$$ is needed, which limits the maximum number. Given a string, the task is to count all palindrome sub string in a given string. h> #include <limits. The input is assumed to be an array. com Jun 20, 2017 · Why HackerRank and other coding tests are ageist by Sarah Butcher 20 June 2017 Given his background in financial services technology, you might think that Marc Adler would have no problem walking 'Solutions for HackerRank 30 Day Challenge in Python. Furthermore, the solution utilizes a simple helper function to check if a number actually is a palindrome: [Hackerrank] – Palindrome Index Question: Given a string, identify the index of character to be removed to change the string into a palindrome. Although no one has proved it yet, it is thought that some numbers, like 196, never produce a palindrome. You can also find a solution for others domain and Sub-domain. It's possible that appending a substring costs more than appending a character twice, so you probably should look at A * lookAhead. Add at the end, and return. In the third case, he can buy 3 chocolates for \$ 6. h> #include <string. on the first line, and the contents of input string on the second Oct 19, 2016 · #include <math. (Still work in progress) This is the first example of a snippet: - the title represents in few words which is the exact issue the snippet resolves; it can be something like the name of a method; - the des reg 15:47 keyboard http://www. Short Problem Definition: Roy wanted to increase his typing speed for programming contests. BUT DON’T JUMP directly to the solution. I was able to complete it but did not have time to generate a post. t N \land \text{ isPalindrome}(t)\). For example, “156434651” reads the same from both directions. Some heads-up will go along way. Method … Continue reading "C Program to Check Whether a Number is Apr 22, 2017 · Algorithm, HackerRank Algorithm, HackerRank, Implementation Previous Article HackerRank Problem : Picking Numbers Next Article HackerRank Problem : Insertion Sort – Part 1 Check whether substring(i,j) is a palindrome Don't do it. I don't like that it automates an interview process to a certain extent, as a candidate's potential and skills and experience and fit in the team can't exactly be measured via an automated process but requires actual human to human interaction. Every entry in array represents a digit in input number. Now, write that as a palindrome function that takes a string. Minimum insertions to form a palindrome | DP-28 Given a string str , the task is to find the minimum number of characters to be inserted to convert it to palindrome. &q=python+code. We are dividing by 2 because we were using half-lengths instead of lengths. 0 short palindrome - hackerRank - world code sprint #5 - add comments to review the code, and see if there is any design defects, improvements - shortPalindrome4A. Shape Stack. Given a sentence check whether it is Pangram or not. That's it. Printing all of them will be quite hard as for example if the string is "aaaaaa" then every substring is a palindrome, also printing the length of each palindrom and the position in the string where it starts is also quite hard as if every substring is a palindrome then there can be, if all the letters are the same, (N*(N+1))/2 palindromes, and that can be about 5*10^11. com/how tujhe kitna chahe aur hum, Jun 14, 2019 · Tujhe Kitna Chahein Aur Lyrics from the movie Kabir Singh: The song is sung by Jubin Nautiyal, Lyrics are Written by Mithoon and the Music was composed by Mithoon. I haven't benchmark it but my suspicion is that if num2str appends digits (instead of prepending) and reverses the string as a final step, Oct 08, 2016 · On Hackerrank, I don't necessarily hate it as a tool, but just the questions that get asked through it. For the first two cases, the string is already a palindrome so no swaps are needed. GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together. Link Game of Thrones - I Complexity: time complexity is O(N); space complexity is O(1) Execution: A palindrome must by definition have an even number of letters. Mar 24, 2019 · Java String Reverse HackerRank Solution in Java Problem:- A palindrome is a word, phrase, number, or other sequence of characters which reads the same backward or forward. Apr 05, 2013 · A palindrome is a string that is spelled the same forward and backward. Improve this sample solution and post your code through Disqus. Task 6. Now he can use his 1 unused wrapper and the 1wrapper of the new piece of chocolate to get one more piece of chocolate. For example, if the input number is “2 3 5 4 5”, the output should be “2 3 6 3 2”. If you are a moderator please see our troubleshooting guide. Lets define the difference between their positions: (cat A, mouse), (cat B, mouse). Jun 30, 2019 · In this video, I have solved hackerrank sparse arrays problem by applying prepressing technique. Both ways yield the same result. Solution Cats and the mouse moves with the same speed. From right to left, it becomes 121-. tujhe kitna chahe aur hum, Jun 14, 2019 · Tujhe Kitna Chahein Aur Lyrics from the movie Kabir Singh: The song is sung by Jubin Nautiyal, Lyrics are Written by Mithoon and the Music was composed by Mithoon. , hackerrank hello world solution, day 0 hello world. Before we go further, let us understand with few examples: I was solving a problem @Hackerrank and came across the below question: You will be given a string representation of a number and a maximum number of changes you can make. ***Solution to Day 21 skipped, because Python implementation was not available at the time of completion. The A simple speedup is achieved by observing that at least one divisor i must be i>=100 and i^2<=palindrome. Pangram is a sentence which contains every letter of the alphabet. JAVAAID - Coding Interview Preparation 2,833 views Mar 27, 2019 · Valid Palindrome II - 刷题找工作 EP60 - Duration: 8:13. GitHub is home to over 50 million developers working together to host and review code, manage projects, and build software together. scatter palindrome hackerrank

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# Moderate Pie Charts Solved QuestionData Interpretation Discussion

Common Information

Answer the questions on the basis of the information given below.

Pie chart l and Pie chart ll show the break up — according to different expenditure heads and savings of the incomes of Mr. and Mrs. Anand respectively. Pie chart III shows the break up — according to the type of savings — of the total savings of the couple (i.e., the savings of Mr. and Mrs. Anand put together).

 Q. Common Information Question: 3/4 If for an income of up to Rs. 1 lakh, no tax is charged and for any income above Rs. 1 lakh, the rate of tax for males and females is 30% and 20010 respectively of the income in excess of Rs.1 lakh, then what is the ratio of the income of Mr. Anand to that of Mrs. Anand?
 ✖ A. 3 : 4 ✔ B. 5 : 4 ✖ C. 4 : 5 ✖ D. None of these

Solution:
Option(B) is correct

Taxes constitute 18% of Mr. Anand's income and rate of tax is 30% beyond 1 lakh.

⇒ 18% of Income = 30% of (Income - one lakh)

⇒ 30000 = 12% of Income

⇒ Income= Rs.2.5 lakh

Similarly, for Mrs. Anand

10% of income = 20% of (Income - one lakh)

⇒ 10% of income = 20000

⇒ Income = Rs.2 lakh

Ratio of earnings = 5 : 4

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# Can a language have $\Sigma^{*}$ as its syntactic monoid?

As per the title I was wondering if it's possible for a language $L \subseteq \Sigma^{*}$ to have $\Sigma^{*}$ as its syntactic monoid and if so could one give an example of such a language? I first thought that this was probably an easy question with a simple answer but I haven't been able to make much progress with it, maybe it has a simple answer and I am just overlooking it?

If we look at the syntactic congruence $\sigma_L = \{(w,z) \in \Sigma^{*} \times \Sigma^{*}: (\forall u, v \in \Sigma^{*}) \; uwv \in L \Leftrightarrow uzv \in L\}$ we see that in order to have $w \cong_{\sigma_{L}} z \Leftrightarrow w = z$ we must have that $(\forall w, z \in \Sigma^{*} \; w \not = z) \; (\exists u, v \in \Sigma^{*})\; uwv \in L \Leftrightarrow uzv \notin L$. Which seems like quite a strong condition. It's also clear that such a language couldn't be regular as it is known that a language is regular if and only if it has a finite syntactic monoid.

• There is a mistake in your last statement: you just need the existence of a pair (u,v) to distinguish 2 elements (w,z), not all possible pairs. The negation of $\forall$ is $\exists$. The precise statement is: $(\forall w\neq z)(\exists (u,v)) uwv\in L \Leftrightarrow uzv\notin L$ May 8 '13 at 13:44
• Yes, you're right. I have edited my question to fix that. May 13 '13 at 15:45
• The language of palindromes over a non-unary alphabet works: cs.stackexchange.com/a/33417/683. May 6 '18 at 8:21

Consider $\{i\#a\#w: w_i = a\}$, where $i$ is an integer indicating index in a word (say, written in unary), $a$ is a single letter and $w$ is a word. This language says that at $i$-th place the word $w$ has letter $a$.

If $a \neq b$ then $a,b$ differ at some position $i$ and you can say $i \# a_i \# a \in L$ while $i \# a_i \# b \notin L$. Or, they can differ at length, but then you talk about the longer string.

This works for any alphabet with at least two characters; for unary alphabets you can use powers of two, squares etc.

• I don't think it works: as soon as you use three #, then you are out of the language, and all words become equivalent. More generally, any language assuming a particular number of occurence of some letter cannot have A* as syntactic monoid. May 13 '13 at 22:13
• dkuper: No, $w$ can contain many $\#$. Only the first two $\#$ count in a word, they indicate division to $i,a$ and $w$ (in fact, the $\#$ between $a$ and $w$ is unneccessary). May 13 '13 at 22:18
• ah ok then it works, thanks (I cannot cancel the downvote until the answer is edited...) May 13 '13 at 22:24

It seems to work to take $L=\{ww: w\in\Sigma^* \text{and$|ww|$is a power of$2$}\}$.

First, we can show that if $|u|>|v|$ then they are not equivalent. Indeed, there is $x$ such that $|uxux|$ is a big power of $2$, say $2^{|u|+|v|}$. Therefore, $uxux\in L$.

But then the length of $vxux$ cannot be power of $2$, because its difference to $2^{|u|+|v|}$ is only $|u|-|v|$. Therefore, if we take $y=xux$, we have $uy\in L$ and $vy\notin L$.

Now it suffices to show that words of the same length are not equivalent. Let $u\neq v$ with $|u|=|v|$, and let $x$ such that $|ux|$ is a power of $2$ (and then so is $|uxux|$). Then you can see that $(u,v)\notin\sigma_L$ because $uxux\in L$ and $uxvx\notin L$.

• Could you explain why $uu \in L$, I'm not sure that the length of $uu$ has to be a power of 2. May 13 '13 at 15:46
• oups sorry, yes you're right we first need to complete u with a word x to reach a power of 2, I edit the answer May 13 '13 at 22:09


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# Defining a function via restrictions of many bijections

I'm trying to define a certain surjective map from $(0,1) \to (0,1)$. For any $(a,b) \subseteq [0,1]$, there's a bijection $(a,b) \rightarrow (a,b) \cup (\frac{1}{3},\frac{2}{3})$. Is there a way to define these bijections such that they're all "compatible"? Basically I'm searching for a well-defined function that on intervals of the above form has the same behavior as the above? Thank you for any help/advice!

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The bijections would have to be of various types, since the union $(a,b) \cup (\frac13,\frac23)$ might be two intervals, or a single interval, and the relative positions of $a,b,\frac13,\frac23$ determine this. It also is unclear what you are asking, is it for a single map $f:[0,1]\to (0,1)$ whose restrictions to each of the intervals formed by $a,b$ is a bijection of the form above? –  coffeemath Aug 2 '13 at 20:16
@coffeemath Thanks for your comment. Yes, I'm looking for a single function. I've also simplified the question a bit - i've decided that I'm not so concerned with the endpoints. –  Vien Nguyen Aug 2 '13 at 20:30
I think "compatible" is really vague here. –  Tunococ Aug 2 '13 at 21:38
@Tunococ Thanks for asking for clarification. What I mean is that the function $f: (0,1) \rightarrow (0,1)$ that I'm looking for, when restricted to any $(a,b)$, should be exactly the bijection $(a,b) \rightarrow (a,b) \cup (\frac{1}{3},\frac{2}{3})$. My questions is basically "Are there ways of choosing these bijections $(a,b) \rightarrow (a,b) \cup (\frac{1}{3},\frac{2}{3})$ such that the above is true? –  Vien Nguyen Aug 2 '13 at 22:13
Definitely there is not. You can first pick $(a, b) = (0, 1)$. That defines the whole function. Then it is impossible that the restrictions of that function to $(0, 1/3)$ and $(2/3, 1)$ are bijections. –  Tunococ Aug 2 '13 at 22:25

Let $I=(\frac13,\frac23)$ and $J=(a,b)$, and assume $f$ is the map from $(0,1)$ to itself which gives a "compatible choice" for all the bijections, by which is meant that the restriction of the single map $f$ to the domain of each suppoped bijection gives that bijection.

The requirements then are that:

[1] For any $J$ the map $f:J \to J \cup I$ be a bijection.

Now note that $I \cup I=I.$ so taking $J=I$ in [1] gives that $f:I \to I$ is a bijection.

Next take any interval $K$ which is a proper subset of $I$, and note that $K \cup I=I$, so that applying [1] with $J=K$ gives that $f:K \to I$ is a bijection. This is a contradiction, since $K$ is a proper subset of $I$ and $f$ is already a bijection from $I$ to $I$.

To bring out the contradiction: Choose $x$ in $I$ but not in $K$. Then $f(x) \in I$, so that since $f:K \to I$ is onto there is $y \in K$ for which $f(y)=f(x)$. This contradicts that $f$ is a bijection on $I$, since $x \neq y$ by our choice.

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Thank you @coffemath ! I'll keep this in mind for later. –  Vien Nguyen Aug 2 '13 at 22:18
@VienNguyen It seems interesting why you were trying to find such $f$ with those bijections. Maybe if you post another question covering the job these bijections were trying to do, someone could give help on reformulating some similar question which had a positive answer. –  coffeemath Aug 2 '13 at 22:35
This came out of a question that my undergrad research advisor asked me to think about, i.e. whether or not there are open maps from [0,1] to the real line. Keeping in mind that (0,1) and the real line are homeomorphic, my idea was to map 0 and 1 separately into (1/3,2/3) here, but that didn't seem to work out XD. I think I want to think about this some more before asking the MSE community. But thank you for the help! –  Vien Nguyen Aug 5 '13 at 2:55

If (1/3, 2/3) is a proper subset of (a, b), then use the identity map.

Otherwise, divide the domain interval (a, b) into two parts, mapping the first part onto (a, b) using scaling, and mapping the second part onto (1/3, 2/3) - (a, b) using scaling and translation.

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This just shows for any $(a,b)$ there is such a bijection, but does not settle whether all such may be chosen "compatibly" as asked in the OP. –  coffeemath Aug 2 '13 at 22:00
Fair comment. I guess what is needed is to define "compatible functions". Plainly not all bijections would be "compatible" in the naive sense of the word. E.g., a continuous bijection would presumably not be compatible with a non-continuous bijection. –  Nick R Aug 2 '13 at 22:15
@NickR thanks for helping out, and sorry I wasn't more clear with defining "compatible". coffeemath's definition in his/her answer is what I meant. –  Vien Nguyen Aug 2 '13 at 22:20


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# Revision history [back]

I find a the final the problem. In fact there is a bug where you want to make the boot procedure. You have to specified the image that your bootable volume use to boot correctly on you volum.

So the correct command is:

nova boot --flavor 2 --image <id of your image> --key_name mykey --block_device_mapping vda=13:::0 boot-from-vol-test

I think it will be used for some peoples...

I find a at the final the problem. In fact there is a bug where you want to make the boot procedure. You have to specified the image that your bootable volume use to boot correctly on you volum.

So the correct command is:

nova boot --flavor 2 --image <id of your image> --key_name mykey --block_device_mapping vda=13:::0 boot-from-vol-test

I think it will be used for some peoples...

I find at the final the problem. In fact there is a bug where you want to make the boot procedure. You have to specified the image that your bootable volume use to boot correctly on you volum.volume.

So the correct command is:

nova boot --flavor 2 --image <id of your image> --key_name mykey --block_device_mapping vda=13:::0 boot-from-vol-test

I think it will be used for some peoples...


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# Elementary problem with Fibonacci numbers

I need help in proving one elementary result with Fibonacci numbers. Prove that for $n>2$, the product $F_1 \cdot F_2 \cdots F_n$ cannot be a perfect square, where $F_1 = F_2 = 1, F_{n+1}=F_n + F_{n-1}$.

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Take the largest prime $p$ up to $n$ (which is greater than $n/2$ by Bertrand's postulate) and notice that since the Fibonacci sequence is a divisibility sequence: $gcd(F_p,F_k)=F_{gcd(p,k)}=1$ for $k\neq p$ then if $\prod F_k$ is a perfect square so is $F_p$, but according to this theorem the only non-trivial square in the Fibonacci sequence is 144 and so you get the result.

Remark: The paper "Diophantine equations with products of consecutive terms in Lucas sequences" by F. Luca, T.N. Shorey determines all products of consecutive Fibonacci numbers which are perfect powers.

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Thank you! Although I am sure that this question should be more elementary than the COHN Theorem, which was open question for decades... –  Bogdan Grechuk Sep 13 '10 at 18:45
Interestingly, from elementery identity F_{n+1}*F_{n-1} - F_n^2 = (-1)^n it follows (without COHN Theorem) that F_{n+1} and F_{n-1} cannot be both exact squares, so if we would have prime p and p+2 greater than n/2, the same agrument would finish the proof ... But twin prime conjecture is a little bit harder than COHN Theorem :) –  Bogdan Grechuk Sep 13 '10 at 18:52
I haven't thought about this much, but I couldn't find something simpler. Do you have any reason to believe the problem has an elementary solution? –  Gjergji Zaimi Sep 13 '10 at 19:33
Yes, I have. It is in the book with problems for mathematical olympiads. I prepare high-school students for olympiads and the next topic will be Fibonacci numbers, so I try to find appropriate problems. –  Bogdan Grechuk Sep 14 '10 at 9:37


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## Linear Algebra and Its Applications, Exercise 2.3.10

Exercise 2.3.10. The set of all 2 by 2 matrices forms a vector space under the standard rules for multiplying two matrices and multiplying a matrix by a scalar. Find a basis for the space and describe the subspace spanned by the set of all matrices $U$ in echelon form.

Answer: Any 2 by 2 matrix

$A = \begin{bmatrix} a&b \\ c&d \end{bmatrix}$

can be represented as a linear combination of four matrices as follows:

$A = \begin{bmatrix} a&b \\ c&d \end{bmatrix} = a \begin{bmatrix} 1&0 \\ 0&0 \end{bmatrix} + b \begin{bmatrix} 0&1 \\ 0&0 \end{bmatrix} + c \begin{bmatrix} 0&0 \\ 1&0 \end{bmatrix} + d \begin{bmatrix} 0&0 \\ 0&1 \end{bmatrix}$

These four matrices are linearly independent and form a basis for the space of all 2 by 2 matrices.

The set of 2 by 2 echelon matrices consists of all matrices $U$ of the form

$\begin{bmatrix} a&b \\ 0&d \end{bmatrix}$

where any of $a$, $b$, or $d$ may be zero. The subspace spanned is the set of all upper triangular matrices, and the three matrices

$\begin{bmatrix} 1&0 \\ 0&0 \end{bmatrix} \qquad \begin{bmatrix} 0&1 \\ 0&0 \end{bmatrix} \qquad \begin{bmatrix} 0&0 \\ 0&1 \end{bmatrix}$

serve as a basis for the subspace.

NOTE: This continues a series of posts containing worked out exercises from the (out of print) book Linear Algebra and Its Applications, Third Edition by Gilbert Strang.

If you find these posts useful I encourage you to also check out the more current Linear Algebra and Its Applications, Fourth Edition, Dr Strang’s introductory textbook Introduction to Linear Algebra, Fourth Edition and the accompanying free online course, and Dr Strang’s other books.

This entry was posted in linear algebra. Bookmark the permalink.


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### CHU-IN CHARLES LEE

Department of Mathematics and Statistics, Memorial University of Newfoundland,
St. John's, Newfoundland, Canada A1C 5S7

(Received August 10, 1989; revised November 26, 1990)

Abstract.    The Laplace continued fraction is derived through a power series. It provides both upper bounds and lower bounds of the normal tail probability \bar Phi(x), it is simple, it converges for x > 0, and it is by far the best approximation for x > 3. The Laplace continued fraction is rederived as an extreme case of admissible bounds of the Mills' ratio, \bar Phi(x)/phi(x), in the family of ratios of two polynomials subject to a monotone decreasing absolute error. However, it is not optimal at any finite x. Convergence at the origin and local optimality of a subclass of admissible bounds are investigated. A modified continued fraction is proposed. It is the sharpest tail bound of the Mills' ratio, it has a satisfactory convergence rate for x > 1 and it is recommended for the entire range of x if a maximum absolute error of 10-4 is required.

Key words and phrases:    Admissibility, approximation, convergence, Mills' ratio, optimality, rational bound.

Source ( TeX , DVI , PS )


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# 3

The previous post sketched an application of Jessica's COEDT framework to get rid of one of the assumptions of my argument for CDT=EDT. Looking at the remaining assumptions of my argument, the hardest one to swallow was implementability: the idea that when the agent implements a mixed strategy, its randomization is successfully controlling for any factors other than those involved in the decision to use that particular mixed strategy. Stated in bayes-net terms, the action has no parents other than the decision.

I stated that the justification of the assumption had to do with the learnability of the causal connections. I then went on to discuss some issues in learning counterfactuals, but not in a way which directly addressed the implementability assumption.

The present post discusses aspects of learning which are more relevant to the implementability assumption. Actually, though, these considerations are only arguments for implementability in that they're arguments for CDT=EDT. None of the arguments here are watertight.

Whereas the previous post was largely a response to COEDT, this post is more exclusively talking about CDT=EDT.

# How Should We Learn Counterfactuals?

## When Are Counterfactuals Reasonable?

How do we evaluate a proposed way to take logical counterfactuals? One reason progress in this area has been so slow is that it has been difficult to even state desirable properties of logical counterfactuals in a mathematically concrete way, aside from strong intuitions about how specific examples should go.

However, there is one desirable property which is very clear: counterfacting on what's true should result in what's true. You might get a strange alternative system of mathematics if you ask what things would be like if 2+2=3, but counterfacting on 2+2=4 just gets us mathematics as we know it.

When we consider situations where an agent fully understands what decision problem it's in (so we are assuming that its map corresponds perfectly to the territory), this means that counterfacting on the action which it really takes in that situation, the counterfactual should tell it the true consequences of that action. However, it is less clear how to apply the principle for learning agents.

In the purely Bayesian case, one might argue that the prior is the equivalent of the true circumstance or decision problem; the best an agent can do is to respond as if it were put in situations randomly according to its prior. However, this doesn't give any guarantees about performance in particular situations; in particular, it doesn't give guarantees about learning the right counterfactuals. This becomes a somewhat more pressing concern when we move beyond Bayesian cases to logical induction, since there isn't a prior which can be treated as the true decision problem in the same way.

One might argue, based on the scary door problem from the previous post, that we shouldn't worry about such things. However, I think there are reasonable things we can ask for without going all the way to opening the scary door.

I propose the following principle for learning agents: you should not be able to systematically correct your counterfactuals. The principle is vaguely stated, but my intention is that it be similar to the logical induction criterion in interpretation: there shouldn't be efficient corrections to counterfactuals, just like there shouldn't be efficient corrections to other beliefs.

If we run into sufficiently similar situations repeatedly, this is like the earlier truth-from-truth principle: the counterfactual predictions for the action actually taken should not keep differing from the consequences experienced. The principle is also not so strong that it implies opening the scary door.

## An Example

Consider a very unfair game of matching pennies, in which the other player sees your move before playing. In the setup of Sam's logical induction tiling result, where the counterfactual function can be given arbitrarily, the most direct way to formalize this makes it so that the action takes always gets utility zero, but the other action always would have yielded utility one, if it had been taken.

The CDT agent doesn't know at the time of making the decision whether the payoff will be 0 for heads and 1 for tails, or 1 for heads and 0 for tails. It can learn, however, that which situation holds depends on which action it ends up selecting. This results in the CDT agent acting pseudorandomly, choosing whichever action it least expects itself to select. The randomization doesn't help, and the agent's expected utility for each action converges to 1/2, which is absurd since it always gets utility 0 in reality. This expectation of 1/2 can be systematically corrected to 0.

An EDT agent who understands the situation would expect utility 0 for each action, since it knows this to be the utility of an action if that action is taken. The CDT agent also knows this to be the conditional expected utility if it actually takes an action; it just doesn't care. Although the EDT agent and CDT agent do equally poorly in this scenario, we can add a third option to not play, giving utility 1/4. The EDT agent will keep going after the illusory 1/2 expected utility.

Sam's theorem assumes that we aren't in a situation like this. I'm not sure if it came off this way in Alex's write-up, but Sam tends to talk about cases like this as unfair environments: the way the payoff for actions depends on the action we actually take makes it impossible to do well from an objective standpoint. I would instead tend to say that this is a bad account of the counterfactuals in the situation. If the other player can see your move in matching pennies, you're just going to get 0 utility no matter how you move.

If we think of this as a hopelessly unfair situation, we accept the poor performance of an agent here. If we think of it as a problem with the counterfactuals, we want a CDT agent to be arranged internally such that it couldn't end up with counterfactuals like these. Asking that counterfactuals not be systematically correctible is a way to do this.

It looks like there is already an argument for EDT along similar lines in the academic literature: The Gibbard-Harper Collapse Lemma for Counterfactual Decision Theory.

## Can We Dutch Book It?

We can get a CDT agent to bet against the correctible expectations if we give it a side-channel to bet on which doesn't interfere with the decision problem. However, while this may be peculiar, it doesn't really constitute a Dutch Book against the agent.

I suspect a kind of Dutch Book could be created by asking it to bet in the same act as its usual action (so that it is causally conditioning on the action at the time, and therefore choosing under the influence of a correctable expectation). This could be combined with a side-bet made after choosing. I'm not sure of the details here, though.

# A Condition for Reflective Stability of CDT Is That It Equal EDT

## Sam's Result

Perhaps a stronger argument for requiring CDT counterfactuals to equal EDT conditionals is the way the assumption seems to turn up in expected-value tiling results. I mentioned earlier that Sam's logical induction tiling result uses a related assumption. Here's Alex Appel's explanation of the assumption:

The key starting assumption effectively says that the agent will learn that the expected utility of selecting an action in the abstract is the same as the expected utility of selecting the specific action that it actually selects, even if a finite-sized chunk of the past action string is tampered with. Put another way, in the limit, if the agent assigns the best action an expected utility of 0.7, the agent will have its expected utility be 0.7, even if the agent went off-policy for a constant number of steps beforehand.

The part about "even if a finite-sized chunk of the past action string is tampered with" is not so relevant to the present discussion. The important part is that the expected utility of a specific action is the same as that expected without knowing which action will be selected.

One way that this assumption can be satisfied is if the agent learns to accurately predict which action it will select. The expectation of this action equals the expectation in general because the expectation in general already knows this action will be taken.

Another way this assumption can be satisfied is if the counterfactual expectation of each action which the agent might take equals the evidential expectation of that action. In other words, the CDT expectations equal the EDT expectations. This implies the desired condition because the counterfactual expectations of each action which the agent believes it might take end up being the same. (If there were a significant difference between the expectations, the agent could predict the result of its argmax, and therefore would know which action it will take.)

The assumption could also hold in a more exotic way, where the counterfactual expectations and the evidential expectations are not equal individually, but the differences balance each other out. I don't have a strong argument against this possibility, but it does seem a bit odd.

So, I don't have an argument here that CDT=EDT is a necessary condition, but it is a sufficient one. As I touched on earlier, there's a question of whether we should regard this as a property of fair decision problems, or as a design constraint for the agent. The stronger condition of knowing your own action isn't a feasible design constraint; some circumstances make your action unpredictable (such as "I'll give you \$100 - [the degree of expectation you had of your action before taking that action]"). We can, however, make the counterfactual expectations equal the evidential ones.

## Diff's Tiling Result

I don't want to lean heavily on Sam's tiling result to make the case for a connection between CDT=EDT and tiling, though, because the conclusion of Sam's theorem is that an agent won't envy another agent for its actions, but not that it won't self-modify into that other agent. It might envy another agent for counterfactual actions which are relevant to getting utility. Indeed, counterfactual mugging problems don't violate any of the assumptions of Sam's theorem, and they'll make the agent want to self-modify to be updateless. Sam's framework only lets us examine sequences of actions, and whether the agent would prefer to take a sequence of actions other than its own. It doesn't let us examine whether the agent's own sequence of actions involves taking a screwdriver to its internal machinery.

Diff's tiling result is very preliminary, but it does suggest that the relationship between CDT=EDT and tiling stays relevant when we deal with self-modification. (Diff = Alex Appel) His first assumption states that concrete expected utility of an action takes equals abstract expected utility of taking some action, along very similar lines to the critical assumption in Sam's theorem.

We will have to see how the story plays out with tiling expected utility maximizers.

# The Major Caveat

The arguments in this post are all restricted to moves which the agent continues to take arbitrarily many times as it learns about the situation it is in. The condition for learning counterfactuals, that they not be systematically correctible, doesn't mean anything for actions which you never take. You can't Dutch Book inconsistent-seeming beliefs which are all conditional on something which never happens. And weird beliefs about actions which you never take don't seem likely to be a big stumbling block for tiling results; the formalizations I used to motivate the connection had conditions having to do with actions actually taken.

This is a major caveat to my line of reasoning, because even if counterfactual expectations and conditional expectations are equal for actions which continue to be taken arbitrarily often, CDT and EDT may end up taking entirely different actions in the limit. For example, in XOR Blackmail, CDT refuses to respond to the letter, and EDT responds. Both expect disaster not to occur after their respective actions, and both are right in their utility forecasts.

We can use Jessica's COEDT to define the conditional beliefs for actions we don't take, but where is the argument that counterfactual beliefs must equal these?

We could argue that CDTs, too, should be limits of CDTs restricted to mixed strategies. This is very much the intuition between trembling-hand Nash equilibria. We then argue that CDTs restricted to mixed strategies should take the same actions as EDTs, by the arguments above, since there are no actions which are never taken. This argument might have some force if a reason for requiring CDT to be the limit of CDTs restricted to mixed strategies were given.

My intuition is that XOR blackmail really shouldn't be counted as a counterexample here. It strikes me as a case correctly resolved by UDT, not CDT. Like counterfactual mugging, counterfactual actions of the agent factor in to the utility received by the agent; or, putting it a different way, a copy of the agent is run with spoofed inputs (in contrast with Newcomb's problem, which runs an exact copy, no spoofing). This means that an agent reasoning about the problem should either reason updatelessly about how it should respond to that sort of situation, or doubt its senses (which can be equivalent).

In other words, my intuition is that there is a class of decision problems for which rational CDT agents converge to EDT in terms of actions taken, not only in terms of the counterfactual expectations of those actions. This class would nicely rule out problems requiring updateless reasoning, and include XOR Blackmail among them.


text:
1. Relationships via modulo arithmetic.

Please assist me in solving this question. Thanks.

2. Re: Relationships via modulo arithmetic.

i) If $5 | x - y$ and $7 | x - y$, then $35 | x - y$.

ii) Symmetric: If $x\equiv y \pmod{35}$,

$y\equiv x \pmod{35}$

Transitive: If $x\equiv y \pmod{35}$ and $y\equiv z \pmod{35}$,

$x\equiv z \pmod{35}$

3. Re: Relationships via modulo arithmetic.

Originally Posted by alexmahone
i) If $5 | x - y$ and $7 | x - y$, then $35 | x - y$.

ii) Symmetric: If $x\equiv y \pmod{35}$,

$y\equiv x \pmod{35}$

Transitive: If $x\equiv y \pmod{35}$ and $y\equiv z \pmod{35}$,

$x\equiv z \pmod{35}$


text:
# Describe effective communications strategies for gathering information, educating patients, and the

###### Question:

Describe effective communications strategies for gathering information, educating patients, and the importance of applying these skills

### Why is it important to look at the master chain link in a transaxle?

Why is it important to look at the master chain link in a transaxle?...

### 3. this question is based on the following paragraph. the sentences are numbered to you

3. this question is based on the following paragraph. the sentences are numbered to you answer the question. (1) scientists generally agree that earth is getting warmer due to what's called the greenhouse effect. (2) a greenhouse stays warm because sunlight and heat coming through the glass roof ar...

### The average bond order is the number of bonds between two atoms taking into account resonance. draw

The average bond order is the number of bonds between two atoms taking into account resonance. draw a lewis structure for the acetate ion and answer the questions below. 1. there are equivalent lewis structures for ch3coo- . (number) 2. the average c - o bond order is ....

Lucia wants to spend less than $16 on her order. Which of the following represent amounts that are in Lucia's budget? Choose all the correct answers.... 3 answers ### 2. Laura and Sage both ordered pizza from the same pizza shop. Laura paid$58.50 for 3 pepperoni pizzas and 2 plain pizzas. Sage paid $67 for 2 pepperoni 2. Laura and Sage both ordered pizza from the same pizza shop. Laura paid$58.50 for 3 pepperoni pizzas and 2 plain pizzas. Sage paid \$67 for 2 pepperoni pizzas and 4 plain pizzas. Let x represent the cost of pepperoni pizzas and y represent the cost of plain pizzas. (a) Write a system of equations ...
If someone doesn't help me I'm getting an f on this. if you put in a suspicious link i will get your ip. write solution in Scientific Notation. $If someone doesn't help me I'm getting an f on this. if you put in a suspicious link i will get you$...
Buuin ang mga pangungusap ayon sa wastong ayos ng gamit ng mga pang uring pahambing . husay galang yabongmunggokisigyamanbaitmaputimaputimalakas $Buuin ang mga pangungusap ayon sa wastong ayos ng gamit ng mga pang uring pahambing . husay galan$...


text:
# Trig Exact Values

• Nov 3rd 2008, 11:25 AM
PDBear
Trig Exact Values
How would you find the exact values for sin(67.5)?
• Nov 3rd 2008, 02:04 PM
masters
Quote:

Originally Posted by PDBear
How would you find the exact values for sin(67.5)?

Use half-angle identity $\sin \frac{x}{2}=\pm \sqrt{\frac{1 - \cos x}{2}}$

Now find $\sin\left(\frac{135}{2}\right)$


text: Search for lepton flavour violating decays of heavy resonances and quantum black holes to an $$\mathrm e\mu$$ e μ pair in proton–proton collisions at $$\sqrts=8~\text TeV$$ s = 8 TeV


text:
# Privileged coordinate system (or lack thereof) in general relativity

What does the following statement mean and why is it true?

The Weak Equivalence Principle (WEP) implies that in general curved space-time there is no privileged coordinate system.

I have looked up the WEP -- as far as I can see, it is more or less the Universality of free fall (?) My (probably totally missing the point) interpretation of the statement is that in general curved space-time, you can't do away with the Gravitational Field everywhere simultaneously... But like I said, I am probably barking up the wrong tree here. Grateful if someone could explain!

Context: This was to justify the use of tensor calculus in GR.

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Where is the quote from and what is the context? –  Ben Crowell Apr 10 '13 at 19:15
@BenCrowell: This is taken from some notes taken during a lecture.,as an introduction into tensor calculus/analysis. –  Gene Apr 10 '13 at 19:31
But what is the context? Don't force us to peer through a keyhole. This sentence is presumably taken from a lengthy argument that explains what your prof had in mind. Taken in isolation, the quote overstates the logical link. You can have diffeomorphism invariance without the EP, and ordinary Galilean relativity already forbids the existence of a privileged coordinate system (although some equivalence classes of coordinate systems may be nicer than others). –  Ben Crowell Apr 10 '13 at 21:42

Long shot, since lack of context, but here is my attempt.

Any event can be described with 4 coordinates [x,y,z,t], where [x,y,z] point in some coordinate system and [t] - synchronized clock at event point.

WEP is same thing as universality of free fall.

The universality of free fall, states that all bodies fall with the same acceleration in a gravitational field, independently of their mass and composition, Theory and Experiment in Gravitational Physics, by Clifford M. Will

That means trajectory depends only on its position and velocity. If we need to describe position there is no privileged coordinate system, that will give to us some additional information about event, each coordinate system differ only by some transformation.

In same time we need to combine geometrical properties with physical, position and time, this can be done by use of tensor, which combine spatial position of event [x,y,z] and time. This technique also used in analysis of electromagnetic fields.

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Thank you, Sigrlami! –  Gene Apr 13 '13 at 18:55


text:
# Why Is an Inhomogenous Magnetic Field Used in the Stern Gerlach Experiment?

In the Stern-Gerlach experiment you want the atoms to be deflected depending on the direction of their magnetic dipole moment.

But you get a net force on the magnetic dipole moment only if the magnetic field is non-homogenous.

(image from "Force and Torque on a Magnetic Dipole" (page 26))

If the magnetic field would be homogenous, then the forces ($$d\vec{F}_1$$ and $$d\vec{F}_2$$ in the image above) would excactly cancel each other, and the net force would be zero.

@Thomas Fritsch uploaded a nice picture that provides intuition about the dynamics of the situation. I would just like to add that the force $$\textbf{F}$$ exerted on this infinitesimal loop pictured (which is how we model a single silver atom in the Stern-Gerlach experiment), is classically given by: $$\textbf{F} := \nabla \left( \boldsymbol{\mu} \cdot \textbf{B}\right) \tag{A}$$ where $$\boldsymbol{\mu}$$ is the silver atom's magnetic dipole moment and is a constant vector (that is, it doesn't exhibit spatial variation). You can easily observe that had $$\textbf{B}$$ been a constant vector, we would have $$\textbf{F} := \nabla \left( \boldsymbol{\mu} \cdot \textbf{B}\right) \tag{B} = \left(\boldsymbol{\mu} \cdot \nabla\right) \cdot \textbf{B} = \mu_x \frac{\partial B_x}{\partial x} + \mu_y \frac{\partial B_y}{\partial y} + \mu_z \frac{\partial B_z}{\partial z} = \textbf{0}$$ Thus, the magnetic field has to be inhomogeneous if we wish to observe a noticeable deflection in the atom's trajectory and thus, investigate the distribution of $$\boldsymbol{\mu}$$ for an ensemble of silver atoms.

$$\bbox[4px,border:1px solid black]{\textbf{An additional note on Equation (A)}}$$ Instead of equation $$(A)$$, some authors simply write: $$F_z = \mu_z \left(\frac{\partial B_z}{\partial z}\right) \hat{\textbf{z}}$$ The simplification occurs by the realization that the average force in the $$x$$ and $$y$$ directions vanishes, as a result of spin precession on the same plane.

(Image taken from page 399, Principles of Quantum Mechanics, Shankar)

The simple answer is that the spins are magnetic dipoles, not monopoles. A monopole will feel a force in any field. But a dipole needs a spatially varying field, because otherwise each pole of the dipole would feel an equal and opposite force (and the net force would be zero).


text:
## Rocky Mountain Journal of Mathematics

### A differential inequality and starlikeness of a double integral

#### Abstract

The main objective of this paper is to discuss starlikeness of order $\beta$ of the solutions of a differential equation and, as a consequence, to obtain conditions on the kernel function $g$ such that the function defined by $f(z)=\int_0^1 \int_0^1 g(r,s,z)\,dr\,ds$ is a starlike function of the same order.

#### Article information

Source
Rocky Mountain J. Math., Volume 44, Number 5 (2014), 1653-1659.

Dates
First available in Project Euclid: 1 January 2015

https://projecteuclid.org/euclid.rmjm/1420071559

Digital Object Identifier
doi:10.1216/RMJ-2014-44-5-1653

Mathematical Reviews number (MathSciNet)
MR3295647

Zentralblatt MATH identifier
1303.30018

#### Citation

Verma, Sarika; Gupta, Sushma; Singh, Sukhjit. A differential inequality and starlikeness of a double integral. Rocky Mountain J. Math. 44 (2014), no. 5, 1653--1659. doi:10.1216/RMJ-2014-44-5-1653. https://projecteuclid.org/euclid.rmjm/1420071559

#### References

• R. Fournier and P.T. Mocanu, Differential inequalities and starlikeness, Complex Var. Theor. Appl. 48 (2003), 283–292.
• S.S. Miller and P.T. Mocanu, Differential subordinations–Theory and applications, Marcel Dekker, New York, 1999.
• M. Obradovic, Simple sufficient conditions for univalence, Mat. Vesn. 49 (1997), 241–244.


text:
# Integral containing something over the root of x²-a²

1. Jun 30, 2010

### Telemachus

1. The problem statement, all variables and given/known data
Evaluate the next integrals, expressing it previously in the forms that contains $$\sqrt[ ]{a^2+u^2}$$, $$\sqrt[ ]{a^2-u^2}$$ and $$\sqrt[ ]{u^2-a^2}$$, and then solve it using the integral table;

The exercise which I couldn't solve:

$$\displaystyle\int_{}^{}\displaystyle\frac{x+3}{\sqrt[ ]{x^2+2x}}dx$$

3. The attempt at a solution
I started by completing the square:

$$x^2+2x=(x+1)^2-1$$

Then

$$u^2=(x+1)^2$$
$$u=(x+1)\Rightarrow{x+3=u+2}$$
$$du=dx$$

$$\displaystyle\int_{}^{}\displaystyle\frac{x+3}{\sqrt[ ]{x^2+2x}}dx=\displaystyle\int_{}^{}\displaystyle\frac{u+2}{\sqrt[ ]{u^2-1}}du$$

From here I've tried to solve it by parts
$$t=u+2$$
$$dt=du$$

$$dv=\displaystyle\frac{1}{\sqrt[ ]{u^2-1}}du$$
$$v=\ln|u+\sqrt[ ]{u^2-1}|$$

$$\displaystyle\int_{}^{}\displaystyle\frac{u+2}{\sqrt[ ]{u^2-1}}du=(u+2)\ln|u+\sqrt[ ]{u^2-1}|-\displaystyle\int_{}^{}\ln|u+\sqrt[ ]{u^2-1}|du$$

If I try again by parts with $$-\displaystyle\int_{}^{}\ln|u+\sqrt[ ]{u^2-1}|du$$ it gets more complicated.

So, what do you say?

Bye there.

2. Jun 30, 2010

### Dick

You can do integral u/sqrt(u^2-1) with a simple substitution. So split (u+2)/sqrt(u^2-1) up into two integrals.

3. Jun 30, 2010

### hunt_mat

The integral
$$\int\frac{u+2}{\sqrt{u^{2}-1}}du$$
Can be computed by the substitution
$$u=\cosh v$$
Everything should come out in the wash then

4. Jun 30, 2010

### Telemachus

Thank you both.

This is what I wasn't seeing:
Bye there!

5. Jun 30, 2010

### Telemachus

I've arrived to this solution:

$$\displaystyle\int_{}^{}\displaystyle\frac{x+3}{\sqrt[ ]{x^2+2x}}dx=\sqrt[ ]{(x+1)^2-1}+2\ln|x+1+\sqrt[ ]{(x+1)^2-1}|+C$$

6. Jun 30, 2010

### Dick

Seems ok to me. I would write x^2+2*x instead of (x+1)^2-1. But that's up to you.

7. Jun 30, 2010

### Telemachus

Thanks Dick. BTW nice nickname :D

8. Jul 1, 2010

### gomunkul51

yup, got the same answer !

P.S: anyone knows a program that writes LaTeX and has an intuitive interface? :)

9. Jul 2, 2010

### nekronaut

10. Jul 2, 2010