>> 'set' is now a proper type constructor. Definitions mem_def and >> Collect_def have disappeared. INCOMPATIBILITY, rephrase sets S used as >> predicates by `%x. x : S` and predicates P used as sets by `{x. P x}`. >> For typical proofs, it is often sufficent to prune any tinkering with >> former theorems mem_def and Collect_def. > > The NEWS entry looks a bit too optimistic. The majority of users after > Isabelle2008 will have to change their theories, and need some more > explicit instructions how to do it sucessfully (e.g. port forwards by > eliminating mem_def/Collect_def before making the actual jump into the > new version).
Good question how such explicit instructions could look like. Eliminating mem_def/Collect_def in a first pass is usually not feasible, because the set/pred-ignorant versions of Isabelle tended to move back and forth between both worlds by their automation setup. The migration strategy had always been to adjust terms to respect the set/pred distinction, and then adjust the proofs accordingly. No trick behind it. Florian -- Home: http://www.in.tum.de/~haftmann PGP available: http://home.informatik.tu-muenchen.de/haftmann/pgp/florian_haftmann_at_informatik_tu_muenchen_de
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