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A note on decidability of variables in intuitionistic propositional logic
Author(s) -
Ishii Katsumasa
Publication year - 2018
Publication title -
mathematical logic quarterly
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.473
H-Index - 28
eISSN - 1521-3870
pISSN - 0942-5616
DOI - 10.1002/malq.201700004
Subject(s) - propositional variable , mathematics , decidability , well formed formula , zeroth order logic , propositional calculus , intuitionistic logic , autoepistemic logic , propositional formula , set (abstract data type) , discrete mathematics , intermediate logic , calculus (dental) , computer science , artificial intelligence , programming language , description logic , medicine , dentistry , multimodal logic
An answer to the following question is presented: given a proof Γ ⊢ A in classical propositional logic, for what small set of propositional variables p does it suffice to add all the formulae p ∨ ¬ p to Γ in order to intuitionistically prove A ? This answer is an improvement of Ishihara's result for some cases.