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1

Automating and Computing Paraconsistent Reasoning: Contraction-Free, Resolution and Type Systems

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Kamide N.

Reports on Mathematical Logic

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2010

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vol. 45

PL

Firstly, a contraction-free sequent system G4np for Nelson’s paraconsistent 4-valued logic N4 is introduced by modifying and extending a contraction-free system G4ip for intuitionistic propositional logic. The structural rule elimination theorem for G4np can be shown by combining Dyckhoff and Negri’s result for G4ip and an existing embedding result for N4. Secondly, a resolution system Rnp for N4 is introduced by modifying an intuitionistic resolution system Rip, which is originally introduced by Mints and modified by Troelstra and Schwichtenberg. The equivalence between Rnp and G4np can be shown. Thirdly, a typed λ-calculus for N4 is introduced based on Prawitz’s natural deduction system for N4 via the Curry-Howard correspondence. The strong normalization theorem of this calculus can be proved by using Joachimski and Matthes’ proof method for intuitionistic typed λ-calculi with premutative conversions.

2

AN EIGHT-VALUED PRACONSISTENT LOGIC

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Kamide N.

Reports on Mathematical Logic

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2014

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vol. 49

PL

It is known that many-valued paraconsistent logics are useful for expressing uncertain and inconsistency-tolerant reasoning in a wide range of Computer Science. Some four-valued and sixteen-valued logics have especially been well-studied. Some four-valued logics are not so ne-grained, and some sixteen-valued logics are enough ne-grained, but rather complex. In this paper, a natural eight-valued paraconsistent logic rather than four-valued and sixteen-valued logics is introduced as a Gentzen-type sequent calculus. This eight-valued logic is enough ne-grained and simpler than sixteen-valued logic. A triplet valuation semantics is introduced for this logic, and the completeness theorem for this semantics is proved. The cut-elimination theorem for this logic is proved, and this logic is shown to be decidable.

3

The Logic of Sequences

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Kamide N.

Reports on Mathematical Logic

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2011

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vol. 46

PL

The notion of “sequences” is fundamental to practical reasoning in computer science, because it can appropriately represent “data (information) sequences”, “program (execution) sequences”, “action sequences”, “time sequences”, “trees”, “orders” etc. The aim of this paper is thus to provide a basic logic for reasoning with sequences. A propositional modal logic LS of sequences is introduced as a Gentzen-type sequent calculus by extending Gentzen’s LK for classical propositional logic. The completeness theorem with respect to a sequence-indexed semantics for LS is proved, and the cut-elimination theorem for LS is shown. Moreover, a first-order modal logic FLS of sequences, which is a first-order extension of LS, is introduced. The completeness theorem with respect to a first-order sequence-indexed semantics for FLS is proved, and the cut-elimination theorem for FLS is shown. LS and the monadic fragment of FLS are shown to be decidable.

4

Strong Normalization of a Typed Lambda Calculus for Intuitionistic Bounded Linear-time Temporal Logic

100%

Kamide N.

Reports on Mathematical Logic

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2012

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vol. 47

PL

Linear-time temporal logics (LTLs) are known to be useful for verifying concurrent systems, and a simple natural deduction framework for LTLs has been required to obtain a good computational interpretation. In this paper, a typed -calculus B[l] with a Curry-Howard correspondence is introduced for an in-tuitionistic bounded linear-time temporal logic B[l], of which the time domain is bounded by a fixed positive integer l. The strong normalization theorem for B[l] is proved as a main result. The base logic B[l] is defined as a Gentzen-type sequent calculus, and despite the restriction on the time domain, B[l] can derive almost all the typical temporal axioms of LTLs. The proposed frame-work allows us to obtain a uniform and simple proof-theoretical treatment of both natural deduction and sequent calculus, i.e., the equivalence between them, the cut-elimination theorem, the decidability theorem, the Curry-Howard correspondence and the strong normalization theorem can be obtained uniformly.

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4 Reports on Mathematical Logic

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4 Kamide N.

Automating and Computing Paraconsistent Reasoning: Contraction-Free, Resolution and Type Systems

AN EIGHT-VALUED PRACONSISTENT LOGIC

The Logic of Sequences

Strong Normalization of a Typed Lambda Calculus for Intuitionistic Bounded Linear-time Temporal Logic