Complementation of Büchi automata has been studied for over five decades since the formalism was introduced in 1960. Known complementation constructions can be classified into Ramsey-based, determinization-based, rank-based, and slice-based approaches. Regarding the performance of these approaches, there have been several complexity analyses but very few experimental results. What especially la...

Paredaens and Van Gucht proved that the at relational algebra has the same expressive power as the nested relational algebra as far as queries over at relations and with at results are concerned We provide a new very direct proof of this fact using a simulation technique Our technique is also applied to partially answer a question posed by Suciu and Paredaens regarding the complexity of evaluat...

Monads are used for various applications in computer science, and well-known is e.g. the interpretation of morphisms in the Kleisli category of the term monad as variable substitutions assigning variables to terms. An application building upon this observation is the equivalence between most general unifiers and co-equalizers in this category [13]. In this paper we will use monads with addition...

Spatial constraint systems (scs) are semantic structures for reasoning about spatial and epistemic information in concurrent systems. We develop the theory of scs to reason distributed potentially infinite groups . characterize notion a group agents as infimum set join-preserving functions that represent spaces group. provide an alternative characterization this greatest family satisfy certain ...

The contravariant powerset, and its generalisations Σ to the lattices of open subsets of a locally compact topological space and of recursively enumerable subsets of numbers, satisfy the Euclidean principle that φ ∧ F (φ) = φ ∧ F (>). Conversely, when the adjunction Σ(−) a Σ(−) is monadic, this equation implies that Σ classifies some class of monos, and the Frobenius law ∃x.(φ(x) ∧ ψ) = (∃x.φ(x...

Amongst conformal field theories, there exist logarithmic conformal field theories such as cp,1 models, various WZNW models, and a large variety of statistical models. It is well known that these theories generally contain a Jordan cell structure, which is a reducible but indecomposable representation. Our main aim in this thesis is to address the results and prospects of boundary logarithmic c...

While automata theory often concerns itself with regular predicates, relations corresponding to acceptance by a finite state automaton, in this article I study the regular functions, such relations which are also functions in the set-theoretic sense. Here I present a small (but necessarily infinite) collection of (multi-ary) functions which generate the regular functions under composition. To t...

This paper demonstrates twometa-mathematical propositions concerning the increasingly popular “intuitionistic” (= vague) approaches to fuzzy sets and fuzzy topology, as well as the closely related interval-valued (= grey) sets and interval-valued “intuitionistic” sets: (1) the term “intuitionistic” in these contexts is historically inappropriate given the standard mathematical usage of “intuiti...

This talk aims at presenting a new way of approaching topological structures, induced by recent developments in the eld of lattice-valued topology, and deemed to incorporate in itself both crisp and many-valued settings. Based on category theory and universal algebra, the new framework is called categorically-algebraic (catalg) [9-12], to underline its motivating theories, on one hand, and to d...

We give a Skolemised presentation of Zermelo’s set theory (with notations for comprehension, powerset, etc.) and show that this presentation is conservative w.r.t. the usual one (where sets are introduced by existential axioms). Conservativity is achieved by an explicit deskolemisation procedure that transforms terms and formulæ of the extended language into provably equivalent formulæ of the c...