[isabelle-dev] pred_set_conv – unidirectional rule

Florian Haftmann florian.haftmann at informatik.tu-muenchen.de
Wed Mar 28 21:41:40 CEST 2012

Hi Stefan,

when considering the prospective predicate equivalent to Id, I concluded
that the corresponding pred_set_conv rule should read:

lemma [pred_set_conv]:
  "HOL.eq = (\<lambda>x y. (x, y) \<in> Id)"
  by (auto simp add: Id_def fun_eq_iff)

However, for obvious reasons (LHS!), this should only be applied from
right to left, not the other way round!  Is there a simple way to make
such unidirectional rules possible?  If not, it is not desaster.

All the best,


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