T:Type, L:(T List), x:T. ((null(L)))  (last([x / L]) = last(L)  T) 

latex

ProofTree

Definitions	True, T, False, A  B, P  Q, P & Q, t  T, , P  Q, i > j, Y, ||as||, last(L), A, P  Q, x:A. B(x)
Lemmas	null wf, not wf, le wf, squash wf, select wf, length wf1, select cons tl, non nil length, assert of null, assert wf, not functionality wrt iff