f:(TopTop), n:, l:(Top List). firstn(n;map(f;l)) ~ map(f;firstn(n;l)) 

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Definitions	x:A. B(x), t  T, P  Q, i  j , A  B, A, False, map(f;as), Y, firstn(n;as), if b then t else f fi , tt, P  Q, , P & Q, P  Q, ff, T, True, , , Unit,
Lemmas	nat wf, top wf, nat properties, ge wf, first0, map wf, lt int wf, bool wf, iff transitivity, assert wf, eqtt to assert, assert of lt int, le int wf, le wf, bnot wf, eqff to assert, squash wf, true wf, bnot of lt int, assert of le int