x, y:. (((x = y)))  x  y 

latex

Up	bool 1, bool 1
Definitions	t  T, x:A. B(x), P & Q, P  Q, P  Q, P  Q, a  b  T ,
Lemmas	assert of eq int, not functionality wrt iff, iff functionality wrt iff, nequal wf, eq int wf, assert wf, not wf