L:Top List, n:. ||L||n  (firstn(n;L) ~ L) 

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Definitions	ij, Unit, P  Q, P & Q, P  Q, T, i<j, , ij, b, b, True, Prop, A, False, P  Q, firstn(n;as), AB, ||as||, x:A. B(x), Top, t  T
Lemmas	top wf, length wf1, le wf, bnot wf, assert wf, le int wf, bool wf, lt int wf, assert of le int, bnot of lt int, true wf, squash wf, eqff to assert, iff transitivity, assert of lt int, eqtt to assert, non neg length