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In this article we introduce two new perfect simulation algorithms for chains with infinite memory. Both algorithms belong to the coupling of past procedures. The novelty of our approach is that it allows to include unknown states to the…

Probability · Mathematics 2025-10-30 Emilio De Santis , Kádmo Laxa , Eva Löcherbach

Minimal perfect hash functions provide space-efficient and collision-free hashing on static sets. Existing algorithms and implementations that build such functions have practical limitations on the number of input elements they can process,…

Data Structures and Algorithms · Computer Science 2018-11-06 Antoine Limasset , Guillaume Rizk , Rayan Chikhi , Pierre Peterlongo

The binary string matching problem consists in finding all the occurrences of a pattern in a text where both strings are built on a binary alphabet. This is an interesting problem in computer science, since binary data are omnipresent in…

Data Structures and Algorithms · Computer Science 2008-10-15 Simone Faro , Thierry Lecroq

Password users frequently employ passwords that are too simple, or they just reuse passwords for multiple websites. A common complaint is that utilizing secure passwords is too difficult. One possible solution to this problem is to use a…

Cryptography and Security · Computer Science 2019-06-04 Elan Rosenfeld , Santosh Vempala , Manuel Blum

Oneway real functions are effective maps on positive-measure sets of reals that preserve randomness and have no effective probabilistic inversions. We construct a oneway real function which is collision-resistant: the probability of…

Logic · Mathematics 2025-01-07 George Barmpalias , Xiaoyan Zhang

We consider the Consensus Patterns problem, where, given a set of input strings, one is asked to extract a long-enough pattern which appears (with some errors) in all strings. We prove that this problem is W[1]-hard when parameterized by…

Computational Complexity · Computer Science 2017-02-28 Laurent Bulteau

Strings are widely used in programs, especially in web applications. Integer data type occurs naturally in string-manipulating programs, and is frequently used to refer to lengths of, or positions in, strings. Analysis and testing of…

Logic in Computer Science · Computer Science 2020-07-15 Taolue Chen , Matthew Hague , Jinlong He , Denghang Hu , Anthony Widjaja Lin , Philipp Rummer , Zhilin Wu

Normally, program execution spends most of the time on loops. Automated test data generation devotes special attention to loops for better coverage. Automated test data generation for programs having loops with variable number of iteration…

Software Engineering · Computer Science 2010-11-03 Hitesh Tahbildar , Bichitra Kalita

We present optimal binary pebbling algorithms for in-place reversal (backward traversal) of one-way hash chains. For a hash chain of length $2^k$, the number of hashes performed in each output round does not exceed $\lceil k/2 \rceil$,…

Cryptography and Security · Computer Science 2018-02-13 Berry Schoenmakers

Partial words are sequences over a finite alphabet that may contain wildcard symbols, called holes, which match or are compatible with all letters; partial words without holes are said to be full words (or simply words). Given an infinite…

Discrete Mathematics · Computer Science 2011-08-19 Francine Blanchet-Sadri , Aleksandar Chakarov , Lucas Manuelli , Jarett Schwartz , Slater Stich

Let us call a sequence of numbers heapable if they can be sequentially inserted to form a binary tree with the heap property, where each insertion subsequent to the first occurs at a leaf of the tree, i.e. below a previously placed number.…

Data Structures and Algorithms · Computer Science 2010-07-15 John Byers , Brent Heeringa , Michael Mitzenmacher , Georgios Zervas

Randomized algorithms are often enjoyed for their simplicity, but the hash functions used to yield the desired theoretical guarantees are often neither simple nor practical. Here we show that the simplest possible tabulation hashing…

Data Structures and Algorithms · Computer Science 2011-05-10 Mihai Patrascu , Mikkel Thorup

Due to its low storage cost and fast query speed, hashing has been widely used in large-scale image retrieval tasks. Hash bucket search returns data points within a given Hamming radius to each query, which can enable search at a constant…

Machine Learning · Computer Science 2024-05-07 Ming-Wei Li , Qing-Yuan Jiang , Wu-Jun Li

These lecture notes show that linear probing takes expected constant time if the hash function is 5-independent. This result was first proved by Pagh et al. [STOC'07,SICOMP'09]. The simple proof here is essentially taken from [Patrascu and…

Data Structures and Algorithms · Computer Science 2017-05-12 Mikkel Thorup

Vulnerability of dedicated hash functions to various attacks has made the task of designing hash function much more challenging. This provides us a strong motivation to design a new cryptographic hash function viz. HF-hash. This is a hash…

Cryptography and Security · Computer Science 2010-07-21 Dhananjoy Dey , Prasanna Raghaw Mishra , Indranath Sengupta

A function $f : U \to \{0,\ldots,n-1\}$ is a minimal perfect hash function for a set $S \subseteq U$ of size $n$, if $f$ bijectively maps $S$ into the first $n$ natural numbers. These functions are important for many practical applications…

Data Structures and Algorithms · Computer Science 2023-08-08 Giulio Ermanno Pibiri , Roberto Trani

Recently, hashing techniques have gained importance in large-scale retrieval tasks because of their retrieval speed. Most of the existing cross-view frameworks assume that data are well paired. However, the fully-paired multiview situation…

Computer Vision and Pattern Recognition · Computer Science 2018-06-20 Jun Yu , Xiao-Jun Wu , Josef Kittler

We consider the problem of the unification modulo an equational theory ACh, which consists of a function symbol $h$ that is homomorphic over an associative-commutative operator $+$. Since the unification modulo ACh theory is undecidable, we…

Logic in Computer Science · Computer Science 2020-10-14 Ajay Kumar Eeralla , Christopher Lynch

This paper proposes round-hashing, which is suitable for data storage on distributed servers and for implementing external-memory tables in which each lookup retrieves at most a single block of external memory, using a stash. For data…

Data Structures and Algorithms · Computer Science 2018-05-09 Roberto Grossi , Luca Versari

Minwise hashing (MinHash) is an important and practical algorithm for generating random hashes to approximate the Jaccard (resemblance) similarity in massive binary (0/1) data. The basic theory of MinHash requires applying hundreds or even…

Machine Learning · Statistics 2021-09-09 Xiaoyun Li , Ping Li