Greg Restall (Melbourne) will present "isomorphisms in a category of propositions and proofs" at 11 on 2 March in Old Arts 156.

\nAbstract: In this talk\, I show how a category of propositions and classical proofs can give rise to three different hyperintensional notions of sameness of content. One of these notions is very fine-grained\, going so far as to distinguish p and p&\;p\, while identifying other distinct pairs of formulas\, such as p&and\;q and q&and\;p\; p \;and ¬\;¬\;p\; or ¬\;(p&and\;q) \;and ¬\;p&or\;¬\;q. Another relation is more coarsely grained\, and gives the same account of identity of content as equivalence in Angell&rsquo\;s logic of analytic containment. A third notion of sameness of content is defined\, which is intermediate between Angell&rsquo\;s and Parry&rsquo\;s logics of analytic containment. Along the way we show how purely classical proof theory gives resources to define hyperintensional distinctions thought to be the domain of properly non-classical logics.

\n ORGANIZER;CN=Shawn Standefer: METHOD:PUBLISH END:VEVENT END:VCALENDAR