changeset 30093 | ecb557b021b2 |
parent 30079 | 293b896b9c25 |
child 30128 | 365ee7319b86 |
--- a/src/HOL/Nat.thy Tue Feb 24 11:12:58 2009 -0800 +++ b/src/HOL/Nat.thy Wed Feb 25 06:53:15 2009 -0800 @@ -280,6 +280,9 @@ lemma diff_add_0: "n - (n + m) = (0::nat)" by (induct n) simp_all +lemma diff_Suc_1 [simp]: "Suc n - 1 = n" + unfolding One_nat_def by simp + text {* Difference distributes over multiplication *} lemma diff_mult_distrib: "((m::nat) - n) * k = (m * k) - (n * k)"