Abstract
In this paper we explore a generalization of traditional abduction which can simultaneously perform two different tasks: (i) given an unprovable sequent Γ⊢G, find a sentence H such that Γ,H⊢G is provable (hypothesis generation); (ii) given a provablesequent Γ⊢G, find a sentence H such that Γ⊢H and the proof of Γ,H⊢G is simpler than the proof of Γ⊢G (lemma generation). We argue that the two tasks should not be distinguished, and present a general procedure for finding suitable hypotheses or lemmas. When the original sequent is provable, the abduced formula can be seen as a cut formula with respect to Gentzen's sequent calculus, so the abduction method is cut-based. Our method is based on the tableau-like system KE and we argue for its advantages over existing abduction methods based on traditional Smullyan-style Tableaux.
Original language | English |
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Pages (from-to) | 537-560 |
Number of pages | 24 |
Journal | Logic Journal of the IGPL |
Volume | 16 |
Issue number | 6 |
DOIs | |
State | Published - 2008 |
Bibliographical note
Funding Information:∗Partly supported by CNPq grant PQ 301294/2004-6 and FAPESP project 04/14107-2. 1“Abduction consists in studying facts and devising a theory to explain them.” (C. P. Peirce, Collected Papers, vol. V, par. 145.) “Abduction is the process of forming an explanatory hypothesis. It is the only logical operation which introduces any new idea” (C. P. Peirce, Collected Papers, vol. V, par. 171).
Funding
∗Partly supported by CNPq grant PQ 301294/2004-6 and FAPESP project 04/14107-2. 1“Abduction consists in studying facts and devising a theory to explain them.” (C. P. Peirce, Collected Papers, vol. V, par. 145.) “Abduction is the process of forming an explanatory hypothesis. It is the only logical operation which introduces any new idea” (C. P. Peirce, Collected Papers, vol. V, par. 171).
Funders | Funder number |
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Fundação de Amparo à Pesquisa do Estado de São Paulo | 04/14107-2 |
Conselho Nacional de Desenvolvimento Científico e Tecnológico | PQ 301294/2004-6 |