Preface Maciej Liskiewicz and Rudiger Reischuk, Special Issue Editors EditorialNotes Pages: 209 - 210
Leftist Grammars and the Chomsky Hierarchy Tomasz JurdzinskiKrzysztof Lorys OriginalPaper Pages: 233 - 256
Polynomial-Space Decidable Membership Problems for Recurrent Systems over Sets of Natural Numbers Daniel Meister OriginalPaper Pages: 257 - 289
On the Power of Unambiguity in Alternating Machines Holger SpakowskiRahul Tripathi OriginalPaper Pages: 291 - 326
Logspace Optimization Problems and Their Approximability Properties Till Tantau OriginalPaper Pages: 327 - 350
Average-Case Non-Approximability of Optimisation Problems Birgit Schelm OriginalPaper Pages: 351 - 368
Exact Algorithms for Graph Homomorphisms Fedor V. FominPinar HeggernesDieter Kratsch OriginalPaper Pages: 381 - 393