CPO-models for second order lambda calculus with recursive types and subtyping
Critical theories of varieties of semigroups satisfying a permutation identity.
Curry algebras
In [6] da Costa has introduced a new hierarchy , of logics that are both paraconsistent and paracomplete. Such logics are now known as non-alethic logics. In this article we present an algebraic version of the logics and study some of their properties.
Cylindric probability algebras.
Dal superamento del riduzionismo insiemistico alla ricerca di una più ampia e profonda comprensione tra matematici e studiosi di altre discipline scientifiche ed umanistiche
Proponiamo in questa Nota un quadro assiomatico aperto e non riduzionista, che si basa sulle idee primitive di qualità e relazione, in cui speriamo sia possibile innestare i concetti fondamentali della Matematica, della Logica e dell’Informatica (di cui diamo solo alcuni primissimi esempi). Auspichiamo che sviluppando liberamente tale quadro sia possibile giungere ad un fruttuoso confronto critico delle idee fondamentali delle diverse discipline scientifiche ed umanistiche, non ristretto agli «specialisti...
Das Entscheidungsproblem der Klasse von Formeln, die höchstens zwei Primformeln enthalten.
Data types as lattices : retractions, closures and projections
De la notion d'opération à celle d'opérateur ou à la recherche de formalismes intrinsèques
Decidability and definability results related to the elementary theory of ordinal multiplication
The elementary theory of ⟨α;×⟩, where α is an ordinal and × denotes ordinal multiplication, is decidable if and only if . Moreover if and respectively denote the right- and left-hand divisibility relation, we show that Th and Th are decidable for every ordinal ξ. Further related definability results are also presented.
Decidability and structure
Decidability and undecidability of theories of abelian groups with predicates for subgroups
Decidability of equational theories of coverings of semigroup varieties.
Decidability of the HD0L ultimate periodicity problem
In this paper we prove the decidability of the HD0L ultimate periodicity problem.
Decidability of the rings of real algebraic and p-adic algebraic integers.
Decidability of weak equational theories
Decidability problems for the variety generated by tournaments.
Decidable Theories of Preordered Fields.
Deciding inclusion of set constants over infinite non-strict data structures
Various static analyses of functional programming languages that permit infinite data structures make use of set constants like Top, Inf, and Bot, denoting all terms, all lists not eventually ending in Nil, and all non-terminating programs, respectively. We use a set language that permits union, constructors and recursive definition of set constants with a greatest fixpoint semantics in the set of all, also infinite, computable trees, where all term constructors are non-strict. This...
Deciding whether a relation defined in Presburger logic can be defined in weaker logics
We consider logics on and which are weaker than Presburger arithmetic and we settle the following decision problem: given a k-ary relation on and which are first order definable in Presburger arithmetic, are they definable in these weaker logics? These logics, intuitively, are obtained by considering modulo and threshold counting predicates for differences of two variables.
Decision problems among the main subfamilies of rational relations
We consider the four families of recognizable, synchronous, deterministic rational and rational subsets of a direct product of free monoids. They form a strict hierarchy and we investigate the following decision problem: given a relation in one of the families, does it belong to a smaller family? We settle the problem entirely when all monoids have a unique generator and fill some gaps in the general case. In particular, adapting a proof of Stearns, we show that it is recursively decidable whether...