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New applications of the wreath product of forest algebras

Howard Straubing (2013)

RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications

We give several new applications of the wreath product of forest algebras to the study of logics on trees. These include new simplified proofs of necessary conditions for definability in CTL and first-order logic with the ancestor relation; a sequence of identities satisfied by all forest languages definable in PDL; and new examples of languages outside CTL, along with an application to the question of what properties are definable in both CTL and LTL.

New kinds of hybrid filters of EQ-algebras

Akbar Paad (2024)

Mathematica Bohemica

The main goal of this paper is to introduce hybrid positive implicative and hybrid implicative (pre)filters of EQ-algebras. In the following, some characterizations of this hybrid (pre)filters are investigated and it is proved that the quotient algebras induced by hybrid positive implicative filters in residuated EQ-algebras are idempotent and residuated EQ-algebra. Moreover, the relationship between hybrid implicative prefilters and hybrid positive implicative prefilters are discussed and it is...

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.

Niven’s Theorem

Artur Korniłowicz, Adam Naumowicz (2016)

Formalized Mathematics

This article formalizes the proof of Niven’s theorem [12] which states that if x/π and sin(x) are both rational, then the sine takes values 0, ±1/2, and ±1. The main part of the formalization follows the informal proof presented at Pr∞fWiki (https://proofwiki.org/wiki/Niven’s_Theorem#Source_of_Name). For this proof, we have also formalized the rational and integral root theorems setting constraints on solutions of polynomial equations with integer coefficients [8, 9].

Non additive ordinal relations representable by lower or upper probabilities

Andrea Capotorti, Giulianella Coletti, Barbara Vantaggi (1998)

Kybernetika

We characterize (in terms of necessary and sufficient conditions) binary relations representable by a lower probability. Such relations can be non- additive (as the relations representable by a probability) and also not “partially monotone” (as the relations representable by a belief function). Moreover we characterize relations representable by upper probabilities and those representable by plausibility. In fact the conditions characterizing these relations are not immediately deducible by means...

Non-axiomatizability of real spectra in λ

Timothy Mellor, Marcus Tressl (2012)

Annales de la faculté des sciences de Toulouse Mathématiques

We show that the property of a spectral space, to be a spectral subspace of the real spectrum of a commutative ring, is not expressible in the infinitary first order language λ of its defining lattice. This generalises a result of Delzell and Madden which says that not every completely normal spectral space is a real spectrum.

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