1713822
A fast regular expression indexing engine
In this paper; we describe the design, architecture, and lessons learned from the implementation of a fast regular-expression indexing engine FREE. FREE uses a prebuilt index to identify the text data units which may contain a matching string and only examines these further. In this way, FREE shows orders of magnitude performance improvement in certain cases over standard regular expression matching systems, such as lex, awk and grep.
1089297
Automatic identification of user goals in Web search
There has been recent interests in studying the "goal" behind a user's Web query, so that this goal can be used to improve the quality of a search engine's results. Previous studies have mainly focused on using manual query-log investigation to identify Web query goals. In this paper we study whether and how we can automate this goal-identification process. We first present our results from a human subject study that strongly indicate the feasibility of automatic query-goal identification. We then propose two types of features for the goal-identification task: user-click behavior and anchor-link distribution. Our experimental evaluation shows that by combining these features we can correctly identify the goals for 90% of the queries studied.
398600
What's new on the web?: the evolution of the web from a search engine perspective
We seek to gain improved insight into how Web search engines shouldcope with the evolving Web, in an attempt to provide users with themost up-to-date results possible. For this purpose we collectedweekly snapshots of some 150 Web sites over the course of one year,and measured the evolution of content and link structure. Our measurements focus on aspects of potential interest to search engine designers: the evolution of link structure over time, the rate ofcreation of new pages and new distinct content on the Web, and the rate of change of the content of existing pages under search-centric measures of degree of change.Our findings indicate a rapid turnover rate of Web pages, i.e.,high rates of birth and death, coupled with an even higher rate ofturnover in the hyperlinks that connect them. For pages that persistover time we found that, perhaps surprisingly, the degree of contentshift as measured using TF.IDF cosine distance does not appear to beconsistently correlated with the frequency of contentupdating. Despite this apparent non-correlation, the rate of content shift of a given page is likely to remain consistent over time. That is, pages that change a great deal in one week will likely change by a similarly large degree in the following week. Conversely, pages that experience little change will continue to experience little change. We conclude the paper with a discussion of the potential implications ofour results for the design of effective Web search engines.
6528301
Energy Efficient Broadcast in Wireless Ad hoc Networks with Hitch-hiking
In this paper, we have proposed a novel concept called Hitch-hiking in order to reduce the energy consumption of broadcast application for wireless networks. Hitch-hiking takes advantage of the physical layer design that facilitates the combining of partial signals to obtain the complete information. The concept of combining partial signals using maximal ratio combiner [13] has been used to improve the reliability of the communication channel but has never been exploited to reduce energy consumption. We propose a centralized heuristic algorithm called Wireless Multicast with Hitch-hiking (WMH) to construct an energy efficient tree using Hitch-hiking and also present a distributed version of the heuristic. We also evaluate the proposed heuristics through simulation. Simulation results show that Hitch-hiking can reduce the transmission cost of broadcast by as much as 50%. Further, we propose and evaluate a protocol called PSBT that reduces energy consumption of broadcast by eliminating redundancy in receive operation. Finally, we propose an algorithm that takes advantage of both Hitch-hiking and PSBT in conserving energy.
9493395
3-D Dynamic Mesh Compression using Wavelet-Based Multiresolution Analysis
In this paper, we present a wavelet-based progressive compression method for 3-D dynamic meshes. Our method exploits the spatial and temporal redundancy. We encode the geometry of base mesh, the wavelet coefficients and the connectivity of each resolution level in order to reduce the spatial redundancy of intra meshes. For inter mesh coding, we encode the differences of geometry of base meshes and of their wavelet coefficients between adjacent frames to reduce the temporal redundancy. Our proposal is based on the wavelet-based multiresolution analysis which uses a perfect reconstruction filter bank and therefore it enables not only progressive representation but also lossless compression. The simulation results demonstrate that the proposed method is applicable to lossy and lossless compression of 3-D dynamic meshes.
361499
Energy Efficient Broadcast in Wireless Ad hoc Networks with Hitch-hiking
In this paper, we propose a novel concept called Hitch-hiking in order to reduce the energy consumption of broadcast application for wireless networks. Hitch-hiking takes advantage of the physical layer design that facilitates the combining of partial signals to obtain the complete information. The concept of combining partial signals using maximal ratio combiner [15] has been used to improve the reliability of the communication link but has never been exploited to reduce energy consumption in broadcasting over wireless ad hoc networks. We study the advantage of Hitch-hiking for the scenario when the transmission power level of nodes is fixed as well as the scenario when the nodes can adjust their power level. For both scenarios, we show that Hitch-hiking is advantageous and have proposed algorithms to construct broadcast tree with Hitch-hiking taken into consideration. For fixed transmission power case, we propose and analyze a centralized heuristic algorithm called SPWMH (Single Power Wireless Multicast with Hitch-hiking) to construct a broadcast tree with minimum forwarding nodes. For the latter case, we propose a centralized heuristic algorithm called Wireless Multicast with Hitch-hiking (WMH) to construct an energy efficient tree using Hitch-hiking and also present a distributed version of the heuristic. We also evaluate the proposed heuristics through simulation. Simulation results show that Hitch-hiking can reduce the transmission cost of broadcast by as much as 50%. Further, we propose and evaluate a protocol called Power Saving with Broadcast Tree (PSBT) that reduces energy consumption of broadcast by eliminating redundancy in receive operation. Finally, we propose an algorithm that takes advantage of both Hitch-hiking and PSBT in conserving energy.
122713
Joint transmitter and receiver optimization in additive cyclostationary noise
A joint optimization of transmitter and receiver is considered for strictly band-limited linear modulations in additive cyclostationary noise. Under the assumptions that the period of the cyclostationarity of the noise is the same as the inverse of the symbol transmission rate and that the noise has a positive-definite autocorrelation function, the optimum transmitter and receiver waveforms that jointly minimize the mean-squared error at the output of the linear receiver are derived with the data sequence modeled as a wide-sense stationary (WSS) colored random process and the channel modeled as a linear time-invariant system with a general frequency-selective impulse response. Numerical results show that this joint optimization technique leads to a significant performance improvement over the systems with receiver-only optimization and the systems with no transmitter and receiver optimizations.
45001657
A New Subsumption Method in the Connection Graph Proof Procedure
Compared to most of the other resolution-based proof procedures, the connection graph proof procedure (CGPP) is superior due to its effective search space reduction rules. A test for subsumption in CGPP is sufficiently efficient in comparison with the standard test. But the subsumption with no restriction may cause logical inconsistency. The restriction on subsumption to maintain the consistency has been an open problem since it was first noticed in 1981. We define a newθ-subsumption which maintains the logical consistency and provides the graph transformation method which makes C subsume D with the new definition if C subsumes D with the original definition ofθ-sumsumption. 
 
In the subsumption test in CGPP, it is essential to find a set of pairwise strongly compatible matching substitutions between literals in two clauses. This paper presents an algorithm which finds a set of pairwise strongly compatible matching substitutions efficiently, based on both the reduction of possible matching substitutions and bit operations. The worst-case time complexity of this algorithm is analyzed in terms of the estimated maximal number of string comparisons and it is shown that our complexity is lower than the other algorithms based on the s-link test. 
 
Based on the new definition of subsumption and the improved algorithm for the pairwise strongly compatible test, an unrestricted subsumption algorithm and a restricted subsumption algorithm are suggested.