8724659
Estimating device availability in pervasive peer-to-peer environment
In pervasive computing environments, devices often communicate in a peer-to-peer manner, either for passing messages or collaboratively running applications. For any particular device, information about the availability of other devices can lead to more efficient communication and better execution of distributed tasks. For example, a device can distribute computation tasks to reliable devices and temporarily avoid unreliable ones. Since there usually is not a central server to coordinate or monitor the communication in such environment, a key technical challenge is for each individual device to predict the availability of other devices. In this paper, we describe some methods for predicting the availability of other devices using historic availability data of those devices obtained in routine usage. In this scheme, each device separately maintains data about the past communication with the other devices, and predicts current and future availability using the statistics of those data. These methods do not require any centralized monitoring or extra probing, and thus have very low computation cost. These characteristics make them suitable for small devices in a peer-to-peer environment.
16311352
DIAL 2004 working group report on acquisition quality control
This report summarizes the discussions of the Working Group on Acquisition Quality at the International Workshop on Document Image Analysis for Libraries, Palo Alto, CA, 23-24 January 2004. Acquisition of the image is one of the most time intensive components of forming a digital library, and the quality of the acquisition will affect all later stages of the digital library project. The current state of the art in acquisition is analyzed. Problems and suggested improvements for image acquisition and storage formats and the special problems associated with acquisition from microfilm follows. A list of general suggestions was developed which was complemented by a wish list of things the Working Group would like to see followed in acquisition discussions in the future
15723189
Impact of imperfect OCR on part-of-speech tagging
Part-of-speech (POS) tagging is the foundation of natural language processing (NLP) systems, and thus has been an active area of research for many years. However, one question remains unanswered: How will a POS tagger behave when the input text is not error-free? This issue can be of great importance when the text comes from imperfect sources like optical character recognition (OCR). This paper analyzes the performance of both individual POS taggers and combination systems on imperfect text. Experimental results show that a POS tagger's accuracy decreases linearly with the character error rate and the slope indicates a tagger's sensitivity to input text errors.
40938143
Automating the analysis of voting systems
Voting is a well-known technique to combine the decisions of peer experts. It is used in fault tolerant applications to mask errors from one or more experts using n-modular redundancy (NMR) and n-version programming. Voting strategies include: majority, weighted voting, plurality; instance runoff voting, threshold voting, and the more general weighted k-out-of-n systems. Before selecting a voting schema for a particular application, we have to understand the various tradeoffs and parameters and how they impact the correctness, reliability, and confidence in the final decision made by a voting system. In this paper, we propose an enumerated simulation approach to automate the behavior analysis of voting schemas with application to majority and plurality voting. We conduct synthetic studies using a simulator that we develop to analyze results from each expert, apply a voting mechanism, and analyze the voting results. The simulator builds a decision tree and uses a depth-first traversal algorithm to obtain the system reliability among other factors. We define and study the following behaviors: 1) the probability of reaching a consensus, "Pc"; 2) reliability of the voting system, "R"; 3) certainly index, "T"; and 4) the confidence index, "C". The parameters controlling the analysis are the number of participating experts, the number of possible output symbols that can be produced by an expert, the probability distribution of each expert's output, and the voting schema. The paper presents an enumerated simulation approach for analyzing voting systems which can be used when the use of theoretical models are challenged by dependencies between experts or uncommon probability distributions of the expert's output.
8341476
Active document layout synthesis
Document layout analysis has been researched for many years. However, there is little work on the reverse of document layout analysis: document layout synthesis, whose goal is to generate logically correct and aesthetically appealing layout given the text/image contents and the flexible layout template. This paper introduces a new automatic document layout synthesis method, which can actively pursue the optimal text block height-width tradeoff simultaneously with the block position adjustment. The key idea is to use a cluster of linear functions to approximate the nonlinear height-width curve. Then two-pass simplex algorithm is used to solve the layout synthesis problem. This method has a wide range of applications, such as variable data printing (VDP), automatic table formatting, and automating document layout ground truth generation.
21113165
Graphical representations of electronic search patterns
Increasing numbers of researchers and developers are collecting data that trace the processes of humancomputer interactions. Although a variety of methods are used to collect such data, all researchers share common problems in representing and analyzing continuous streams of data. A set of methods and tools for graphically representing the search patterns of users interacting with a variety of databases and hypertexts is under development as part of ongoing research in electronic information seeking. The methodology described in this article involves defining state spaces of user options within a system, capturing keystrokes or mouse moves as raw data, coding these data into the state spaces, and analyzing user moves through the state space as evidence of goal-directed informationseeking strategies and patterns. A tool for displaying user moves through a state space has been developed and is described. The tool graphically represents data in a variety of formats, allowing human pattern recognition capabilities to be applied for data analysis. Graphs can be represented for individual searches or for multiple searches done by either a single searcher or by several searchers working on the same search task.
1008302
Straight-Line Drawing Algorithms for Hierarchical Graphs and Clustered Graphs
AbstractHierarchical graphs and clustered graphs are useful non-classical graph models for structured relational information. Hierarchical graphs are
graphs with layering structures; clustered graphs are graphs with
recursive clustering structures. Both have applications in CASE tools, software visualization and VLSI design. Drawing algorithms for hierarchical
graphs have been well investigated. However, the problem of planar straight-line representation has not been solved completely. In this paper we answer the question: does every planar hierarchical graph admit a planar straight-line
hierarchical drawing? We present an algorithm that constructs
such drawings in linear time. Also, we answer a basic question for clustered
graphs, that is, does every planar clustered graph admit a planar
straight-line drawing with clusters drawn as convex polygons? We
provide a method for such drawings based on our algorithm for
hierarchical graphs.
7595419
Efficient Computation of k-Medians over Data Streams Under Memory Constraints
In this paper, we study the problem of efficiently computing k-medians over high-dimensional and high speed data streams. The focus of this paper is on the issue of minimizing CPU time to handle high speed data streams on top of the requirements of high accuracy and small memory. Our work is motivated by the following observation: the existing algorithms have similar approximation behaviors in practice, even though they make noticeably different worst case theoretical guarantees. The underlying reason is that in order to achieve high approximation level with the smallest possible memory, they need rather complex techniques to maintain a sketch, along time dimension, by using some existing off-line clustering algorithms. Those clustering algorithms cannot guarantee the optimal clustering result over data segments in a data stream but accumulate errors over segments, which makes most algorithms behave the same in terms of approximation level, in practice. We propose a new grid-based approach which divides the entire data set into cells (not along time dimension). We can achieve high approximation level based on a novel concept called (1−∊)-dominant. We further extend the method to the data stream context, by leveraging a density-based heuristic and frequent item mining techniques over data streams. We only need to apply an existing clustering once to computing k-medians, on demand, which reduces CPU time significantly. We conducted extensive experimental studies, and show that our approaches outperform other well-known approaches.
16928019
Map Displays for Information Retrieval
The focus of this article is to develop a map display for to stack in the dark, without knowing what stacks that information retrieval. Through an examination of relawe have walked through. We can get a few books each tionships among visual displays, information retrieval, time and walk out of the library to see if the book we and browsing, advantages of visual displays for informaare searching for is among them. If not, we have to walk tion retrieval are characterized as (1) the ability to conin again, based on our knowledge and our previous experivey a large amount of information in a limited space, (2) the potential to reveal semantic relationships of terms ence, to a location where we hope the book would be. In and documents, and (3) the facilitation of browsing and this situation, success in finding a book greatly depends perceptual inferences on retrieval interfaces. These adon whether we can walk to the right place in the dark (to vantages are further demonstrated through a map disgenerate a good query), and whether we know how to play generated by a neural network’s self-organizing aladjust our locations until we get to the right place (to gorithm. The map display detects complex relationships among given documents, and reveals the relationships modify queries interactively) . through a spatial arrangement of terms abstracted from Can we turn on the light for such a library? Can we the documents. The map display also provides interdevelop some visible cues in our retrieval systems so that active tools to allow the user to interact with the underlywe can use our perception for information seeking in ing information. Examples of the map displays show that the digital environment? Answers to these questions may such map displays can be used both as an overview tool and an access or exploration tool, and the map displays reside in the recent advance of information technology. will likely increase the amount of information that the ‘‘Information processing has been evolving from numeriuser is willing to browse. cal computation to character handling, and now to visual information processing’’ (Kunii, 1989). As a result, visualization will become ‘‘the second computer revolution’’ Introduction (Friedhoff & Benzon, 1989). Computers are expected to be used to reveal associations and properties of electronic The world in which we live is a visual world. We look, information to allow people to use their visual capabilities we see, and we find things. Even for written information, for information seeking (Veith, 1988). we expect to see it on tangible media stored in visible locations. We have developed a whole set of perception This article discusses using some mapping techniques and association techniques to get what we need from the to create visual displays for textual information stored in environment. However, when we search information by the computer. The focus of the article is on the developcomputer, all the things, information, media, locations, ment of a map display for information retrieval. The map as well as their relationships, become invisible; all the display attempts to show both contents and semantic clues for visual perceptions and associations disappear. structures of a document space by mapping major conWe heavily rely on our competence to generate queries cepts and documents of a document space to a two-dimenand the computer’s ability to match the queries with inforsional map. It preserves, as faithfully as possible, documation stored in the computer. At best, when interaction ment semantic relationships and reveals these relationis involved, we can modify queries based on the retrieved ships through various visual components of the display. results of a previous query. This is like searching books By communicating a spatial metaphor to the user and in a library without light. We can walk around from stack making information in a document space graphically visible, the map display provides a visual guide to help the user perceive contents and structures of the document Received May 26, 1995; revised December 18, 1995; accepted Decemspace. ber 18, 1995. In the following, relationships among information retrieval, browsing, and visual displays are discussed first, q 1997 John Wiley & Sons, Inc.
207195547
Graphical table of contents
This paper proposes a graphical table of contents (GTOC) that is functionally analogous to the table of contents. The proposed GTOC can be generated automatically from the text of documents. It visualizes document contents and relationships to allow easy access of underlying documents. It also provides various interactive tools to let the user explore the documents. Issues of how to generate such GTOC include how documents are indexed and organized, how the organized documents are visualized, and what interactive means are needed to provide necessary functionality of GTOC. These issues are discussed in this paper with a GTOC prototype based on Kohonen’s selforganizing featore map algorithm.