scholarly journals Consistency and Decidability in Some Paraconsistent Arithmetics

2021 ◽  
Vol 18 (5) ◽  
pp. 473-502
Author(s):  
Andrew Tedder
Keyword(s):  
Paraconsistent Logics ◽  
Models Of Arithmetic

The standard style of argument used to prove that a theory is unde- cidable relies on certain consistency assumptions, usually that some fragment or other is negation consistent. In a non-paraconsistent set- ting, this amounts to an assumption that the theory is non-trivial, but these diverge when theories are couched in paraconsistent logics. Furthermore, there are general methods for constructing inconsistent models of arithmetic from consistent models, and the theories of such inconsistent models seem likely to differ in terms of complexity. In this paper, I begin to explore this terrain, working, particularly, in incon- sistent theories of arithmetic couched in three-valued paraconsistent logics which have strong (i.e. detaching) conditionals.

scholarly journals Useful Four-Valued Extension of the Temporal Logic KtT4

2018 ◽  
Vol 47 (1) ◽  
Author(s):  
Vincent Degauquier
Keyword(s):  
Modal Logic ◽  
Temporal Logic ◽  
Paraconsistent Logics ◽  
Accessibility Relation

The temporal logic KtT4 is the modal logic obtained from the minimal temporal logic Kt by requiring the accessibility relation to be reflexive (which corresponds to the axiom T) and transitive (which corresponds to the axiom 4). This article aims, firstly, at providing both a model-theoretic and a proof-theoretic characterisation of a four-valued extension of the temporal logic KtT4 and, secondly, at identifying some of the most useful properties of this extension in the context of partial and paraconsistent logics.

Models of arithmetic and upper bounds for arithmetic sets

1994 ◽  
Vol 59 (3) ◽  
pp. 977-983 ◽  
Author(s):  
Alistair H. Lachlan ◽  
Robert I. Soare
Keyword(s):  
Upper Bound ◽  
Upper Bounds ◽  
Models Of Arithmetic

AbstractWe settle a question in the literature about degrees of models of true arithmetic and upper bounds for the arithmetic sets. We prove that there is a model of true arithmetic whose degree is not a uniform upper bound for the arithmetic sets. The proof involves two forcing constructions.

On LP-models of arithmetic

2008 ◽  
Vol 73 (1) ◽  
pp. 212-226 ◽  
Author(s):  
J. B. Paris ◽  
A. Sirokofskich
Keyword(s):  
Congruence Relations ◽  
Classical Models ◽  
Models Of Arithmetic

AbstractWe answer some problems set by Priest in [11] and [12], in particular refuting Priest's Conjecture that all LP-models of Th(ℕ) essentially arise via congruence relations on classical models of Th(ℕ). We also show that the analogue of Priest's Conjecture for IΔ0 + Exp implies the existence of truth definitions for intervals [0, a] ⊂eM ⊨ IΔ0 + Exp in any cut [0, a] ⊂eK ⊆eM closed under successor and multiplication.

Paraconsistency, self-extensionality, modality

2018 ◽  
Vol 28 (5) ◽  
pp. 851-880
Author(s):  
Arnon Avron ◽  
Anna Zamansky
Keyword(s):  
Intuitionistic Logic ◽  
Modal Logics ◽  
The Other ◽  
Paraconsistent Logics ◽  
Classical Negation ◽  
Inconsistent Theories ◽  
Replacement Property ◽  
General Method

Abstract Paraconsistent logics are logics that, in contrast to classical and intuitionistic logic, do not trivialize inconsistent theories. In this paper we take a paraconsistent view on two famous modal logics: B and S5. We use for this a well-known general method for turning modal logics to paraconsistent logics by defining a new (paraconsistent) negation as $\neg \varphi =_{Def} \sim \Box \varphi$ (where $\sim$ is the classical negation). We show that while that makes both B and S5 members of the well-studied family of paraconsistent C-systems, they differ from most other C-systems in having the important replacement property (which means that equivalence of formulas implies their congruence). We further show that B is a very robust C-system in the sense that almost any axiom which has been considered in the context of C-systems is either already a theorem of B or its addition to B leads to a logic that is no longer paraconsistent. There is exactly one notable exception, and the result of adding this exception to B leads to the other logic studied here, S5.

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