Falsification, natural deduction and bi-intuitionistic logic

2013 ◽  
Vol 26 (1) ◽  
pp. 425-450 ◽  
Author(s):  
Heinrich Wansing
Keyword(s):  
Intuitionistic Logic ◽  
Natural Deduction

scholarly journals Normalization as a consequence of cut elimination

2009 ◽  
Vol 86 (100) ◽  
pp. 27-34
Author(s):  
Mirjana Borisavljevic
Keyword(s):  
Intuitionistic Logic ◽  
Natural Deduction ◽  
Cut Elimination ◽  
Deduction System ◽  
Normalization Theorem ◽  
Natural Deduction System

Pairs of systems, which consist of a system of sequents and a natural deduction system for some part of intuitionistic logic, are considered. For each of these pairs of systems the property that the normalization theorem is a consequence of the cut-elimination theorem is presented.

scholarly journals A Formalisation of Weak Normalisation (with Respect to Permutations) of Sequent Calculus Proofs

2000 ◽  
Vol 3 ◽  
pp. 1-26
Author(s):  
A.A. Adams
Keyword(s):  
Fixed Points ◽  
Intuitionistic Logic ◽  
Natural Deduction ◽  
Sequent Calculus ◽  
The State ◽  
Original Presentation

AbstractDyckhoff and Pinto present a weakly normalising system of reductions on derivations are characterised as the fixed points of the composition of the Prawitz translations into natural deduction and back. This paper presents a formalisation of the system, including a proof of the Weak normalisation property for the formalisation. More details can be found in earlier work by the author. The formalisation has been kept as closes as possible to the original presentation to allow an evaluation of the state of proof assistance for such methods, and to ensure similarity of methods, and not merely similarly of results. The formalisation is restricted to the implicational fragment of intuitionistic logic.

scholarly journals Arithmetic Formulated Relevantly

2021 ◽  
Vol 18 (5) ◽  
pp. 154-288
Author(s):  
Robert Meyer
Keyword(s):  
Intuitionistic Logic ◽  
Natural Deduction ◽  
Relevant Logic ◽  
Peano Arithmetic ◽  
Critical Problem ◽  
First Order ◽  
Order Form ◽  
Relevant Implication ◽  
Relevant Logics ◽  
Natural Way

The purpose of this paper is to formulate first-order Peano arithmetic within the resources of relevant logic, and to demonstrate certain properties of the system thus formulated. Striking among these properties are the facts that (1) it is trivial that relevant arithmetic is absolutely consistent, but (2) classical first-order Peano arithmetic is straightforwardly contained in relevant arithmetic. Under (1), I shall show in particular that 0 = 1 is a non-theorem of relevant arithmetic; this, of course, is exactly the formula whose unprovability was sought in the Hilbert program for proving arithmetic consistent. Under (2), I shall exhibit the requisite translation, drawing some Goedelian conclusions therefrom. Left open, however, is the critical problem whether Ackermann’s rule γ is admissible for theories of relevant arithmetic. The particular system of relevant Peano arithmetic featured in this paper shall be called R♯. Its logical base shall be the system R of relevant implication, taken in its first-order form RQ. Among other Peano arithmetics we shall consider here in particular the systems C♯, J♯, and RM3♯; these are based respectively on the classical logic C, the intuitionistic logic J, and the Sobocinski-Dunn semi-relevant logic RM3. And another feature of the paper will be the presentation of a system of natural deduction for R♯, along lines valid for first-order relevant theories in general. This formulation of R♯ makes it possible to construct relevantly valid arithmetical deductions in an easy and natural way; it is based on, but is in some respects more convenient than, the natural deduction formulations for relevant logics developed by Anderson and Belnap in Entailment.

scholarly journals Natural deduction for bi-intuitionistic logic

2017 ◽  
Vol 25 ◽  
pp. S72-S96 ◽  
Author(s):  
Luca Tranchini
Keyword(s):  
Intuitionistic Logic ◽  
Natural Deduction

Proofs, Snakes and Ladders

Dialogue ◽  
1974 ◽  
Vol 13 (4) ◽  
pp. 723-731 ◽  
Author(s):  
Alasdair Urquhart
Keyword(s):  
Normal Form ◽  
Intuitionistic Logic ◽  
Natural Deduction ◽  
Tree Structure ◽  
Deduction System ◽  
Syntactical Structure ◽  
Form Theorem ◽  
Structural Identity ◽  
Natural Deduction System ◽  
Normal Form Theorem

Anyone who has worked at proving theorems of intuitionistic logic in a natural deduction system must have been struck by the way in which many logical theorems “prove themselves.” That is, proofs of many formulas can be read off from the syntactical structure of the formulas themselves. This observation suggests that perhaps a strong structural identity may underly this relation between formulas and their proofs. A formula can be considered as a tree structure composed of its subformulas (Frege 1879) and by the normal form theorem (Gentzen 1934) every formula has a normalized proof consisting of its subformulas. Might we not identify an intuitionistic theorem with (one of) its proof(s) in normal form?

Natural Deduction for Dual-intuitionistic Logic

Studia Logica ◽  
2012 ◽  
Vol 100 (3) ◽  
pp. 631-648 ◽  
Author(s):  
Luca Tranchini
Keyword(s):  
Intuitionistic Logic ◽  
Natural Deduction

scholarly journals An Alternative Natural Deduction for the Intuitionistic Propositional Logic

2016 ◽  
Vol 45 (1) ◽  
Author(s):  
Mirjana Ilić
Keyword(s):  
Intuitionistic Logic ◽  
Propositional Logic ◽  
Natural Deduction ◽  
Sequent Calculus ◽  
Intuitionistic Propositional Logic ◽  
Deduction System ◽  
Natural Deduction System

A natural deduction system NI, for the full propositional intuitionistic logic, is proposed. The operational rules of NI are obtained by the translation from Gentzen’s calculus LJ and the normalization is proved, via translations from sequent calculus derivations to natural deduction derivations and back.

A lambda proof of the P-W theorem

2000 ◽  
Vol 65 (4) ◽  
pp. 1841-1849
Author(s):  
Sachio Hirokawa ◽  
Yuichi Komori ◽  
Misao Nagayama
Keyword(s):  
Intuitionistic Logic ◽  
Natural Deduction ◽  
Modus Ponens ◽  
Logical System ◽  
System P

AbstractThe logical system P-W is an implicational non-commutative intuitionistic logic denned by axiom schemes B − (b → c) → (a → b) → a → c. B′ = (a → b) → (b → c) → a → c. I - a → a with the rules of modus ponens and substitution. The P-W problem is a problem asking whether α - β holds if α → β and β → α are both provable in P-W. The answer is affirmative. The first to prove this was E. P. Martin by a semantical method.In this paper, we give the first proof of Martin's theorem based on the theory of simply typed λ-calculus. This proof is obtained as a corollary to the main theorem of this paper, shown without using Martin's Theorem, that any closed hereditary right-maximal linear (HRML) λ-term of type α → α is βη-reducible to λxx. Here the HRML λ-terms correspond, via the Curry-Howard isomorphism, to the P-W proofs in natural deduction style.

Sequent combinators: a Hilbert system for the lambda calculus

2000 ◽  
Vol 10 (1) ◽  
pp. 1-79 ◽  
Author(s):  
HEALFDENE GOGUEN ◽  
JEAN GOUBAULT-LARRECQ
Keyword(s):  
Computer Science ◽  
Programming Languages ◽  
Intuitionistic Logic ◽  
Natural Deduction ◽  
Lambda Calculus ◽  
First Order ◽  
Uniform Approach ◽  
Explicit Substitutions ◽  
Suitable Framework ◽  
Proof Terms

This paper introduces Hilbert systems for λ-calculus, called sequent combinators, addressing many of the problems of Hilbert systems that have led to the more widespread adoption of natural deduction systems in computer science. This suggests that Hilbert systems, with their uniform approach to meta-variables and substitution, may be a more suitable framework than λ-calculus for type theories and programming languages. Two calculi are introduced here. The calculus SKIn captures λ-calculus reduction faithfully, is confluent even in the presence of meta-variables, is normalizing but not strongly normalizing in the typed case, and standardizes. The sub-calculus SKInT captures λ-reduction in slightly less obvious ways, and is a language of proof-terms not directly for intuitionistic logic, but for a fragment of S4 that we name near-intuitionistic logic. To our knowledge, SKInT is the first confluent, first-order calculus to capture λ-calculus reduction fully and faithfully and be strongly normalizing in the typed case. In particular, no calculus of explicit substitutions has yet achieved this goal.

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