Talk by Peter Schroeder-Heister (LTCS)

Short Title: 
Talk by Peter Schroeder-Heister
Event Date(s): 
Thursday, 19. October 2017 - 14:15

Room 206, Main Building, Hochschulstrasse 4, 3012 Bern

Prof. Dr. Peter Schroeder-Heister (Universität Tübingen)

Intensional aspects of proofs

I plead to give intensional considerations in proof theory, in particular the question of identity of proofs, a stronger stance than it is often given. This is particularly important for philosophical investigations in proof-theoretic semantics. A crucial aspect is what can be counted as a proper step of proof reduction, as this is what constitutes the identity of proofs. I discuss in particular Ekman's paradox, which is an interesting example of a derivation in intuitionistic propositional logic, which is non-normalizable given a (prima facie) plausible extension of the standard notion of reduction.