src/LCF/ex/Ex4.thy
author wenzelm
Sat, 30 Dec 2006 12:38:51 +0100
changeset 21960 0574f192b78a
parent 19755 90f80de04c46
child 27208 5fe899199f85
permissions -rw-r--r--
* Proof General: proper undo of final 'end'; discontinued Isabelle/classic;


header {* Prefixpoints *}

theory Ex4
imports LCF
begin

lemma example:
  assumes asms: "f(p) << p"  "!!q. f(q) << q ==> p << q"
  shows "FIX(f)=p"
  apply (unfold eq_def)
  apply (rule conjI)
  apply (tactic {* induct_tac "f" 1 *})
  apply (rule minimal)
  apply (intro strip)
  apply (rule less_trans)
  prefer 2
  apply (rule asms)
  apply (erule less_ap_term)
  apply (rule asms)
  apply (rule FIX_eq [THEN eq_imp_less1])
  done

end