changeset 38621 | d6cb7e625d75 |
parent 38167 | ab528533db92 |
child 41853 | 258a489c24b2 |
--- a/src/HOL/Library/Nat_Infinity.thy Fri Aug 20 17:46:55 2010 +0200 +++ b/src/HOL/Library/Nat_Infinity.thy Fri Aug 20 17:46:56 2010 +0200 @@ -227,8 +227,10 @@ apply (simp add: plus_1_iSuc iSuc_Fin) done -instance inat :: semiring_char_0 - by default (simp add: of_nat_eq_Fin) +instance inat :: semiring_char_0 proof + have "inj Fin" by (rule injI) simp + then show "inj (\<lambda>n. of_nat n :: inat)" by (simp add: of_nat_eq_Fin) +qed subsection {* Ordering *}