From joe at gilith.com Fri Sep 28 15:59:12 2012 From: joe at gilith.com (Joe Leslie-Hurd) Date: Fri, 28 Sep 2012 08:59:12 -0700 Subject: [opentheory-users] HOL light In-Reply-To: References: <506424E8.4000308@nicta.com.au> Message-ID: Hi Ramana, [cc'ing the opentheory-users mailing list] > The proof-logging fork [of HOL Light] has sets as a > separate type, and the scripts in Model/ haven't been updated yet. Just a brief note on this design decision, because I know the convention in HOL implementations is to use the type 'a -> bool for sets. For the standard theory library I aim to prioritise ease of importing theories into a theorem prover over ease of exporting, and as Michael notes it's easy to "bind" 'a set to 'a -> bool when importing (the other way around would be more difficult). Also, when thinking about how to design reusable theories I thought the extra isolation of a new type would make it easier to derive consequences of sets by theory interpretation (by interpreting a helpful parametric theory type operator to the "set"), and would prevent the accidental inclusion of "ill-formed" terms like "{ x | P x } t" in exported theorems. > So... someone (probably me) just needs to work through the scripts in Model/ > and get them to compile again... I'd be happy to provide tech support for a porting effort to do this. My experience with porting the set theory library in HOL Light is that most tactic proofs are insensitive to the choice of set representation. Cheers, Joe