k:, x, y:k. ((y, x) o (y, x)) = (x.x)  kk 

latex

Definitions	(i, j), i  j < k, AB, f o g, i=j, if b t else f fi, {i..j}, Unit, P  Q, P & Q, False, , b, Prop, t  T, b, x:A. B(x), P  Q, A
Lemmas	assert wf, not wf, bnot wf, assert of eq int, not functionality wrt iff, assert of bnot, iff transitivity, eqff to assert, eqtt to assert, eq int wf, bool wf, ifthenelse wf, compose wf, int seg wf