1lemma app_Nil2 [simp]: "xs @ [] = xs"
2apply(induct_tac xs)
3apply(auto)
4done
5
6lemma app_assoc [simp]: "(xs @ ys) @ zs = xs @ (ys @ zs)"
7apply(induct_tac xs)
8apply(auto)
9done
10
11lemma rev_app [simp]: "rev(xs @ ys) = (rev ys) @ (rev xs)"
12apply(induct_tac xs)
13apply(auto)
14done
15
16theorem rev_rev [simp]: "rev(rev xs) = xs"
17apply(induct_tac xs)
18apply(auto)
19done
20
21end
22