Turku Centre for Computer Science

About: Turku Centre for Computer Science is a facility organization based out in Turku, Finland. It is known for research contribution in the topics: Decidability & Word (group theory). The organization has 382 authors who have published 1027 publications receiving 19560 citations.

Current trends in theoretical computer science: entering the 21st centuary

Abstract: Computational Complexity (E Allender et al.) Formal Specification (H Ehrig et al.) Login in Computer Science (Y Gurevich et al.) Concurrency (M Nielsen et al.) Natural Computing (G Rozenberg et al.) Formal Language Theory (A Salomaa et al.)

Context-free evolutionary grammars and the structural language of nucleic acids

Abstract: This paper introduces and investigates a generative mechanism based on some operations inspired by the large-scale mutations in genomes (deletion, inversion, transposition, duplication). Basic questions regarding these devices and their generated languages are investigated: generative capacity, closure properties, decidability. We also briefly discuss a few problems concerning our model with respect to some structural features of the nucleic acids.

Refinement algebra with operators for enabledness and termination

Abstract: Refinement algebras are abstract algebras for reasoning about programs in a total-correctness framework. We extend a reduct of von Wright's demonic refinement algebra with two operators for modelling enabledness and termination of programs. We show how the operators can be used for expressing relations between programs and apply the algebra to reasoning about action systems.

An extension of context-free grammars with one-sided context specifications

Abstract: The paper introduces an extension of context-free grammars equipped with an operator for referring to the left context of the substring being defined. For example, a rule A->[email protected]?B defines a symbol a, as long as it is preceded by a string defined by B. The conjunction operator in this example is taken from conjunctive grammars (Okhotin, 2001), which are an extension of ordinary context-free grammars that maintains most of their practical properties, including many parsing algorithms. This paper gives two equivalent definitions of grammars with left contexts-by logical deduction and by language equations-and establishes their basic properties, including a transformation to a normal form and a cubic-time parsing algorithm, with a square-time version for unambiguous grammars.

DNA Computing: New Ideas and Paradigms

Abstract: DNA computing is one of the most exciting new developments in computer science, from both technological and theoretical point of view. We begin by observing how the structure of DNA molecules and the technics available for manipulating them are very suitable for computing. We then establish a link with certain fairly old results from computability theory which essentially explain why the main feature of DNA molecules, the Watson-Crick complementarity, gives rise to the Turing-universality of DNA computations. Selected areas of DNA computing, interesting from a theoretical point of view but offering also practical potential, will be briefly examined.