src/HOL/Wellfounded.thy
changeset 39302 d7728f65b353
parent 37767 a2b7a20d6ea3
child 40607 30d512bf47a7
     1.1 --- a/src/HOL/Wellfounded.thy	Mon Sep 13 08:43:48 2010 +0200
     1.2 +++ b/src/HOL/Wellfounded.thy	Mon Sep 13 11:13:15 2010 +0200
     1.3 @@ -781,7 +781,7 @@
     1.4  
     1.5            let ?N1 = "{ n \<in> N. (n, a) \<in> r }"
     1.6            let ?N2 = "{ n \<in> N. (n, a) \<notin> r }"
     1.7 -          have N: "?N1 \<union> ?N2 = N" by (rule set_ext) auto
     1.8 +          have N: "?N1 \<union> ?N2 = N" by (rule set_eqI) auto
     1.9            from Nless have "finite N" by (auto elim: max_ext.cases)
    1.10            then have finites: "finite ?N1" "finite ?N2" by auto
    1.11