Journal ArticleDOI
The complexity of computing maximal word functions
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This paper presents a parallel algorithm for computing maximal word functions for languages recognized by one-way nondeterministic auxiliary pushdown automata (and hence for the class of context-free languages).Abstract:
Maximal word functions occur in data retrival applications and have connections with ranking problems i.e. with problems related to data compression. Compute the maximal word function of a string x with respect to a language L ⊑ Σ* consists in determining the lexicographically greatest word belonging to L, which is smaller than or equal to x.read more
Citations
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Journal ArticleDOI
Non-commutative arithmetic circuits: depth reduction and size lower bounds
TL;DR: In this paper, it was shown that in the non-commutative setting, O(log 2 n) can be reduced to O( log n) if unbounded-fanin gates are allowed.
Journal ArticleDOI
A quasi-polynomial-time algorithm for sampling words from a context-free language
TL;DR: A quasi-polynomial-time algorithm for sampling almost uniformly at random from then-slice of the languageL(G) generated by an arbitrary context-free grammarG, where |G| is a natural measure of the size of grammarG.
Journal ArticleDOI
How Hard Is Computing the Edit Distance
TL;DR: This paper presents a parallel algorithm for computing the edit distance for the class of languages accepted by one-way nondeterministic auxiliary pushdown automata working in polynomial time, a class that strictly contains context?free languages.
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The complexity of obtaining solutions for problems in NP and NL
Birgit Jenner,Jacob Torán +1 more
TL;DR: A screwdriver bit has a threaded portion forming a tap immediately adjacent to the screw engaging end of the screwdriver.
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Compression of samplable sources
TL;DR: In this article, the authors studied the problem of polynomially samplable sources and gave efficient prefix-free compression and decompression algorithms for three classes of such sources (whose support is a subset of {0, 1}n).
References
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Book
Introduction to Automata Theory, Languages, and Computation
TL;DR: This book is a rigorous exposition of formal languages and models of computation, with an introduction to computational complexity, appropriate for upper-level computer science undergraduates who are comfortable with mathematical arguments.
Journal ArticleDOI
The complexity of enumeration and reliability problems
TL;DR: For a large number of natural counting problems for which there was no previous indication of intractability, that they belong to the class of computationally eqivalent counting problems that are at least as difficult as the NP-complete problems.
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The Theory of Parsing, Translation, and Compiling
Alfred V. Aho,Jeffrey D. Ullman +1 more
TL;DR: It is the hope that the algorithms and concepts presented in this book will survive the next generation of computers and programming languages, and that at least some of them will be applicable to fields other than compiler writing.
Journal ArticleDOI
Random generation of combinatorial structures from a uniform
TL;DR: It is shown that exactly uniform generation of ‘efficiently verifiable’ combinatorial structures is reducible to approximate counting (and hence, is within the third level of the polynomial hierarchy).