T:Type, L:(T List). ((null(L)))  (last(L)  L) 

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ProofTree

Definitions	False, A  B, t  T, , i > j, A c B, , x:A. B(x), last(L), (x  l), A, P  Q, x:A. B(x), P & Q, P  Q
Lemmas	null wf, not wf, select wf, le wf, length wf1, non nil length, assert of null, assert wf, not functionality wrt iff