A:Type, as:(A List), a:A, i:. as[i]?a  A 

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Definitions	T, ff, P  Q, P & Q, P  Q, tt, if b then t else f fi , True, False, A, P  Q, , A  B, as[i]?a, t  T, x:A. B(x), Unit, , ,
Lemmas	assert of le int, bnot of lt int, true wf, squash wf, eqff to assert, assert of lt int, eqtt to assert, iff transitivity, bnot wf, le wf, le int wf, select wf, assert wf, bool wf, length wf1, lt int wf, nat wf