Advanced search    

Search: authors:"Pawel Gawrychowski"

13 papers found.
Use AND, OR, NOT, +word, -word, "long phrase", (parentheses) to fine-tune your search.

Towards Unified Approximate Pattern Matching for Hamming and L_1 Distance

Computing the distance between a given pattern of length n and a text of length m is defined as calculating, for every m-substring of the text, the distance between the pattern and the substring. This naturally generalizes the standard notion of exact pattern matching to incorporate dissimilarity score. For both Hamming and L_{1} distance only relatively slow O~(n sqrt{m...

Improved Bounds for Shortest Paths in Dense Distance Graphs

5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 Pawel Gawrychowski, Haim Kaplan, Shay Mozes, Micha Sharir, and Oren Weimann. Voronoi diagrams on planar graphs, and computing the diameter in ... /1.9781611975031.33. Pawel Gawrychowski, Shay Mozes, and Oren Weimann. Submatrix maximum queries in monge matrices are equivalent to predecessor search. In Automata, Languages, and Programming - 42nd International

Fast Entropy-Bounded String Dictionary Look-Up with Mismatches

Ferragina and Rossano Venturini. A simple storage scheme for strings achieving entropy bounds. Theoretical Computer Science, 372(1):115?121, 2007. Johannes Fischer and Pawel Gawrychowski. Alphabet-dependent ... . Willard. Surpassing the information theoretic bound with fusion trees. J. Comput. Syst. Sci., 47(3):424?436, dec 1993. Pawel Gawrychowski, Moshe Lewenstein, and Patrick K. Nicholson. Weighted ancestors in

Edit Distance with Block Operations

We consider the problem of edit distance in which block operations are allowed, i.e. we ask for the minimal number of (block) operations that are needed to transform a string s to t. We give O(log n) approximation algorithms, where n is the total length of the input strings, for the variants of the problem which allow the following sets of operations: block move; block move and...

Slowing Down Top Trees for Better Worst-Case Compression

We consider the top tree compression scheme introduced by Bille et al. [ICALP 2013] and construct an infinite family of trees on n nodes labeled from an alphabet of size sigma, for which the size of the top DAG is Theta(n/log_sigma n log log_sigma n). Our construction matches a previously known upper bound and exhibits a weakness of this scheme, as the information-theoretic lower...

Near-Optimal Distance Emulator for Planar Graphs

Pettie . A hierarchy of lower bounds for sublinear additive spanners . In 28th SODA , pages 568 - 576 , 2017 . Amir Abboud , Pawel Gawrychowski, Shay Mozes, and Oren Weimann . Near-optimal compression for

Dispersion on Trees

In the k-dispersion problem, we need to select k nodes of a given graph so as to maximize the minimum distance between any two chosen nodes. This can be seen as a generalization of the independent set problem, where the goal is to select nodes so that the minimum distance is larger than 1. We design an optimal O(n) time algorithm for the dispersion problem on trees consisting of...

A Family of Approximation Algorithms for the Maximum Duo-Preservation String Mapping Problem

In the Maximum Duo-Preservation String Mapping problem we are given two strings and wish to map the letters of the former to the letters of the latter as to maximise the number of duos. A duo is a pair of consecutive letters that is mapped to a pair of consecutive letters in the same order. This is complementary to the well-studied Minimum Common String Partition problem, where...

Randomized Algorithms for Finding a Majority Element

Given n colored balls, we want to detect if more than n/2 of them have the same color, and if so find one ball with such majority color. We are only allowed to choose two balls and compare their colors, and the goal is to minimize the total number of such operations. A well-known exercise is to show how to find such a ball with only 2n comparisons while using only a logarithmic...

Tight Tradeoffs for Real-Time Approximation of Longest Palindromes in Streams

We consider computing a longest palindrome in the streaming model, where the symbols arrive one-by-one and we do not have random access to the input. While computing the answer exactly using sublinear space is not possible in such a setting, one can still hope for a good approximation guarantee. Our contribution is twofold. First, we provide lower bounds on the space requirements...

Efficiently Finding All Maximal alpha-gapped Repeats

9234 of LNCS , pages 205 - 217 . Springer, 2015 . Pawel Gawrychowski . Pattern matching in Lempel-Ziv compressed strings: Fast, simple, and deterministic . In Proc. ESA , volume 6942 of LNCS , pages 421

Testing Generalised Freeness of Words

Pseudo-repetitions are a natural generalisation of the classical notion of repetitions in sequences: they are the repeated concatenation of a word and its encoding under a certain morphism or antimorphism (anti-/morphism, for short). We approach the problem of deciding efficiently, for a word w and a literal anti-/morphism f, whether w contains an instance of a given pattern...

Finding Pseudo-repetitions

Pseudo-repetitions are a natural generalization of the classical notion of repetitions in sequences. We solve fundamental algorithmic questions on pseudo-repetitions by application of insightful combinatorial results on words. More precisely, we efficiently decide whether a word is a pseudo-repetition and find all the pseudo-repetitive factors of a word.