MFCS
13 years 10 months ago
2001 Springer 
We show that it is not possible to approximate the minimum Steiner tree problem within 1 + 1 162 unless RP = NP. The currently best known lower bound is 1 + 1 400. The reduction i...
MFCS
13 years 10 months ago
2001 Springer
Combinatorial games lead to several interesting, clean problems in algorithms and complexity theory, many of which remain open. The purpose of this paper is to provide an overview...
MFCS
13 years 10 months ago
2001 Springer 
We describe an explicit simulation of 2-way nondeterministic automata by 1-way alternating automata with quadratic blow-up. We first describe the construction for automata on fin...
MFCS
13 years 10 months ago
2001 Springer
Abstract. We prove that the class of context-free languages with polynomially bounded ambiguity (PCFL) is the closure of the class of unambiguous languages (UCFL) under projections...
MFCS
13 years 10 months ago
2001 Springer 
We consider words indexed by linear orderings. These extend finite, (bi-)infinite words and words on ordinals. We introduce finite automata and rational expressions for these w...
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Theoretical Computer Science