Showing papers in "Theoretical Computer Science in 2007"

TL;DR: This paper shows how a resource-oriented logic, separation logic, can be used to reason about the usage of resources in concurrent programs.

TL;DR: It is shown that randomized search heuristics find minimum spanning trees in expected polynomial time without employing the global technique of greedy algorithms.

TL;DR: A weighted version of MSO logic is introduced and it is proved that, for commutative semirings, the behaviours of weighted automata are precisely the formal power series definable with particular sentences of the authors' weighted logic.

TL;DR: A resource-sensitive logic for partial correctness, based on a recent proposal of O'Hearn, adapting separation logic to the concurrent setting is introduced, using a novel ''local'' interpretation of traces which allows accurate reasoning about ownership.

TL;DR: It is shown that for finite state spaces, all three sets of winning states can be computed in polynomial time: type-1 states in linear time, andType-2 and type-3 states in quadratic time, which enable the construction of the winning and spoiling strategies.

TL;DR: A fast and memory-efficient algorithm for lexicographically sorting the suffixes of a string, a problem that has important applications in data compression as well as string matching, that operates in only two integer arrays and has worst-case time complexity O(nlogn).

TL;DR: The fact that a rewrite logic theory's axioms include both equations and rewrite rules provides a useful ''abstraction dial'' to find the right balance between abstraction and computational observability in semantic definitions.

TL;DR: It is shown that this simple task can be in general accomplished by the considered system of robots, but under which conditions can this task be accomplishedby the robots?

TL;DR: This paper shows that one can use gap encoding techniques to obtain constant time rank and select queries in essentially the same space as what is achieved by the best current direct solution (and sometimes less), and extends symbolRank and select to substring rank andSelect, giving several space/time trade-offs for the problem.

TL;DR: In this paper, a reduction from local distributed approximation algorithms for the vertex cover problem to sublinear approximation algorithms was proposed, which can be applied to other problems with local distributed algorithms, such as the dominating set problem.

TL;DR: This paper presents a Hoare-style logic for specifying and verifying how two pointer programs are related, and proves that the Schorr-Waite graph marking algorithm is equivalent to the depth-first traversal.

TL;DR: A generalization of the Burrows-Wheeler Transform to a multiset of words, which allows to define a bijection between the words over a finite alphabet A and the finite multisets of conjugacy classes of primitive words in A^*.

TL;DR: The main results of this paper show that attributed graph transformation with node type inheritance is fully compatible with the existing concept of typed attributedgraph transformation.

TL;DR: It is shown that on average it takes constant time to rearrange the balls to achieve this, and that @e>(2/e)^d^-^1 is sufficient, so that with high probability each ball can be put into one of the two bins assigned to it without any bin overflowing.

TL;DR: If at least a rule from a set of rules associated with a membrane or a region can be used, then at least one rule from that membrane or region must be used , without any other restriction, and this minimal parallelism leads to universality.

TL;DR: It is shown that the state complexity of a combined operation can be very different from the composition of the state complexities of the participating individual operations.

TL;DR: An overview of SOS rule formats and meta-theorems formulated around them is provided, which range from well-definedness of the operational semantics and compositionality of behavioral equivalences to security-, time- and probability-related issues.

TL;DR: It is shown that in a class of hypercube-like interconnection networks called restricted HL-graphs, each pair of vertices are joined by a path in [email protected]?F of every length from 2m-3 to |V([email protected])?F)|-1 for any set F of faulty elements (vertices and/or edges) with |F|@?m-2.

TL;DR: A class of vertex partitioning problems that can be expressed in monadic second order logic (MSOL) are polynomials on graphs of bounded clique-width, which includes coloring, H-free coloring, domatic number and partition into perfect graphs.

TL;DR: In this article, a systematic investigation of completeness and directed completeness of @W-categories is presented, based on the theory of @F-completeness for enriched categories.

TL;DR: A general fault tolerant CDS problem, called k-Connected m-Dominating Set (k-m-CDS), in heterogeneous networks, is studied and two approximation algorithms are presented that have a constant approximation ratio.

TL;DR: In this paper, the (1+1) evolution strategy for minimization in R^n is investigated when it uses isotropically distributed mutation vectors, and it turns out that Gaussian mutations in combination with the 1/5-rule indeed ensure asymptotically optimal runtime; namely, @Q(n) steps/function evaluations are necessary and sufficient to halve the approximation error.

TL;DR: It is proved that the complexity of (fractional) 'multicommodity flows over time' is NP-hard, even for series-parallel networks, and new and efficient algorithms under certain assumptions on the transit times or on the network topology are presented.

TL;DR: In this article, the authors study the problem of rewriting queries using views in the presence of access patterns, integrity constraints, disjunction and negation, and provide asymptotically optimal algorithms for (1) finding minimally containing and (2) maximally contained rewritings respecting the access patterns (which they call executable) and deciding whether an exact executable rewriting exists.

TL;DR: The algorithm is alphabet-independent: it uses only character comparisons, and the complexities do not depend on the alphabet size unless v does, and it can construct the suffix arrays a small block at a time without storing the rest of the suffix array anywhere.

TL;DR: In this article, it was shown that there exists a critical radius r"o"p"t such that for any random geometric graph G(n,r) has optimal cover time of @Q(nlogn) with high probability, where r"c" o"n denotes the critical radius guaranteeing asymptotic connectivity.

TL;DR: This paper proves that for any n≥5 there exists an infinite word over n letters with no factor of its exponent larger than n/(n-1).

TL;DR: The notion of a tile assembly system that computes a function, and issues for systems that compute the sum and product of two numbers are tackled.

TL;DR: In this article, the authors prove a series of normal forms for spiking neural P systems, concerning the regular expressions used in the firing rules, the delay between firing and spiking, the forgetting rules used, and the outdegree of the graph of synapses.

TL;DR: In this paper, Ramaman et al. improved the lower bound for rank and select queries to O(m/t) and O(n/t t ) in the case of m 1-bits, respectively, where t is the number of bits in a bit vector.