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Does anyone know what versions freeze and autofreeze are available in? I have the impression that they are new features (being undocumented).  — Tom 7 14:22, 1 December 2006 (EST)

I think freeze has been available since around 1.5, but it wasn't in 1.4, I'm almost certain. — Rob (and his talk) 18:53, 20 December 2006 (EST)


Can unsoundness also result if there is no autofreeze? I'm not sure what Twelf's behavior was in this case.  — Tom 7 14:22, 1 December 2006 (EST)

It should - you could prove eq (s N) N implied absurd, and then add a case to eq to make that theorem no longer true... — Rob (and his talk) 18:52, 20 December 2006 (EST)
Certainly if it continued to accept the totality of that theorem for the new extended eq. But if any worlds/total/etc. declarations were invalidated by new declarations for a type family, I think that might still be sound. Did Twelf do that? Probably not.  — Tom 7 00:15, 25 December 2006 (EST)