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Complexité de la famille des ensembles de synthèse d'un groupe abélien localement compact

Etienne Matheron (1996)

Studia Mathematica

On montre que si G est un groupe abélien localment compact non diskret à base dénombrable d'ouverts, alors la famille des fermés de synthèse pour l'algèbre de Fourier A(G) est une partie coanalytique non borélienne de ℱ(G), l'ensemble des fermés de G muni de la structure borélienne d'Effros. On généralise ainsi un résultat connu dans le cas du groupe 𝕋.

Complexité des boréliens à coupes dénombrables

Dominique Lecomte (2000)

Fundamenta Mathematicae

Nous donnons, pour chaque niveau de complexité Γ, une caractérisation du type "test d'Hurewicz" des boréliens d'un produit de deux espaces polonais ayant toutes leurs coupes dénombrables ne pouvant pas être rendus Γ par changement des deux topologies polonaises.

Complexity of curves

Udayan B. Darji, Alberto Marcone (2004)

Fundamenta Mathematicae

We show that each of the classes of hereditarily locally connected, finitely Suslinian, and Suslinian continua is Π₁¹-complete, while the class of regular continua is Π₀⁴-complete.

Complexity of the axioms of the alternative set theory

Antonín Sochor (1993)

Commentationes Mathematicae Universitatis Carolinae

If T is a complete theory stronger than ZF Fin such that axiom of extensionality for classes + T + ( X ) Φ i is consistent for 1 i k (each alone), where Φ i are normal formulae then we show AST + ( X ) Φ 1 + + ( X ) Φ k + scheme of choice is consistent. As a consequence we get: there is no proper Δ 1 -formula in AST + scheme of choice. Moreover the complexity of the axioms of AST is studied, e.gẇe show axiom of extensionality is Π 1 -formula, but not Σ 1 -formula and furthermore prolongation axiom, axioms of choice and cardinalities are Π 2 -formulae,...

Complexity of the class of Peano functions

K. Omiljanowski, S. Solecki, J. Zielinski (2000)

Colloquium Mathematicae

We evaluate the descriptive set theoretic complexity of the space of continuous surjections from m to n .

Complexity of λ -term reductions

M. Dezani-Ciancaglini, S. Ronchi Della Rocca, L. Saitta (1979)

RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications

Complexity results for prefix grammars

Markus Lohrey, Holger Petersen (2005)

RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications

Resolving an open problem of Ravikumar and Quan, we show that equivalence of prefix grammars is complete in PSPACE. We also show that membership for these grammars is complete in P (it was known that this problem is in P) and characterize the complexity of equivalence and inclusion for monotonic grammars. For grammars with several premises we show that membership is complete in EXPTIME and hard for PSPACE for monotonic grammars.

Complexity results for prefix grammars

Markus Lohrey, Holger Petersen (2010)

RAIRO - Theoretical Informatics and Applications

Resolving an open problem of Ravikumar and Quan, we show that equivalence of prefix grammars is complete in PSPACE. We also show that membership for these grammars is complete in P (it was known that this problem is in P) and characterize the complexity of equivalence and inclusion for monotonic grammars. For grammars with several premises we show that membership is complete in EXPTIME and hard for PSPACE for monotonic grammars.

Complicated BE-algebras and characterizations of ideals

Yılmaz Çeven, Zekiye Çiloğlu (2015)

Discussiones Mathematicae - General Algebra and Applications

In this paper, using the notion of upper sets, we introduced the notions of complicated BE-Algebras and gave some related properties on complicated, self-distributive and commutative BE-algebras. In a self-distributive and complicated BE-algebra, characterizations of ideals are obtained.

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