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Hierarchies and reducibilities on regular languages related to modulo counting

Victor L. Selivanov (2009)

RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications

We discuss some known and introduce some new hierarchies and reducibilities on regular languages, with the emphasis on the quantifier-alternation and difference hierarchies of the quasi-aperiodic languages. The non-collapse of these hierarchies and decidability of some levels are established. Complete sets in the levels of the hierarchies under the polylogtime and some quantifier-free reducibilities are found. Some facts about the corresponding degree structures are established. As an application,...

Hierarchies and reducibilities on regular languages related to modulo counting

Victor L. Selivanov (2008)

RAIRO - Theoretical Informatics and Applications

We discuss some known and introduce some new hierarchies and reducibilities on regular languages, with the emphasis on the quantifier-alternation and difference hierarchies of the quasi-aperiodic languages. The non-collapse of these hierarchies and decidability of some levels are established. Complete sets in the levels of the hierarchies under the polylogtime and some quantifier-free reducibilities are found. Some facts about the corresponding degree structures are established. As an application, we...

Immunity and Simplicity for Exact Counting and Other Counting Classes

J. Rothe (2010)

RAIRO - Theoretical Informatics and Applications

Ko [26] and Bruschi [11] independently showed that, in some relativized world, PSPACE (in fact, ⊕P) contains a set that is immune to the polynomial hierarchy (PH). In this paper, we study and settle the question of relativized separations with immunity for PH and the counting classes PP, C = P , and ⊕P in all possible pairwise combinations. Our main result is that there is an oracle A relative to which C = P contains a set that is immune BPP⊕P. In particular, this C = P A set is immune to PHA and to ⊕PA. Strengthening...

Lower Space Bounds for Accepting Shuffle Languages

Andrzej Szepietowski (2010)

RAIRO - Theoretical Informatics and Applications

In [6] it was shown that shuffle languages are contained in one-way-NSPACE(log n) and in P. In this paper we show that nondeterministic one-way logarithmic space is in some sense the lower bound for accepting shuffle languages. Namely, we show that there exists a shuffle language which is not accepted by any deterministic one-way Turing machine with space bounded by a sublinear function, and that there exists a shuffle language which is not accepted with less than logarithmic space even if we allow...

New recursive characterizations of the elementary functions and the functions computable in polynomial space.

I. Oitavem (1997)

Revista Matemática de la Universidad Complutense de Madrid

We formulate recursive characterizations of the class of elementary functions and the class of functions computable in polynomial space that do not require any explicit bounded scheme. More specifically, we use functions where the input variables can occur in different kinds of positions ?normal and safe? in the vein of the Bellantoni and Cook's characterization of the polytime functions.

O složitosti

Pavel Pudlák (1988)

Pokroky matematiky, fyziky a astronomie

On Existentially First-Order Definable Languages and Their Relation to NP

Bernd Borchert, Dietrich Kuske, Frank Stephan (2010)

RAIRO - Theoretical Informatics and Applications

Under the assumption that the Polynomial-Time Hierarchy does not collapse we show for a regular language L: the unbalanced polynomial-time leaf language class determined by L equals  iff L is existentially but not quantifierfree definable in FO[<, min, max, +1, −1]. Furthermore, no such class lies properly between NP and co-1-NP or NP⊕co-NP. The proofs rely on a result of Pin and Weil characterizing the automata of existentially first-order definable languages.

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