proposition: Lemma non_cont_ex3: ~ ocontinuous_at (fun t => t *o t) omega0.
proof: Proof. move: OS_omega => oo hyp. move:(oprod_Meq1lt olt_1omega olt_0omega) => ll. move:(proj2 hyp _ ll) => [y ys yp]. by case:(olt_ltT (yp y (oleR (proj31_1 ys)) ys) (oprod2_lt_omega ys ys)). Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat)