MAYBE

Problem:
 active(pairNs()) -> mark(cons(0(),incr(oddNs())))
 active(oddNs()) -> mark(incr(pairNs()))
 active(incr(cons(X,XS))) -> mark(cons(s(X),incr(XS)))
 active(take(0(),XS)) -> mark(nil())
 active(take(s(N),cons(X,XS))) -> mark(cons(X,take(N,XS)))
 active(zip(nil(),XS)) -> mark(nil())
 active(zip(X,nil())) -> mark(nil())
 active(zip(cons(X,XS),cons(Y,YS))) -> mark(cons(pair(X,Y),zip(XS,YS)))
 active(tail(cons(X,XS))) -> mark(XS)
 active(repItems(nil())) -> mark(nil())
 active(repItems(cons(X,XS))) -> mark(cons(X,cons(X,repItems(XS))))
 mark(pairNs()) -> active(pairNs())
 mark(cons(X1,X2)) -> active(cons(mark(X1),X2))
 mark(0()) -> active(0())
 mark(incr(X)) -> active(incr(mark(X)))
 mark(oddNs()) -> active(oddNs())
 mark(s(X)) -> active(s(mark(X)))
 mark(take(X1,X2)) -> active(take(mark(X1),mark(X2)))
 mark(nil()) -> active(nil())
 mark(zip(X1,X2)) -> active(zip(mark(X1),mark(X2)))
 mark(pair(X1,X2)) -> active(pair(mark(X1),mark(X2)))
 mark(tail(X)) -> active(tail(mark(X)))
 mark(repItems(X)) -> active(repItems(mark(X)))
 cons(mark(X1),X2) -> cons(X1,X2)
 cons(X1,mark(X2)) -> cons(X1,X2)
 cons(active(X1),X2) -> cons(X1,X2)
 cons(X1,active(X2)) -> cons(X1,X2)
 incr(mark(X)) -> incr(X)
 incr(active(X)) -> incr(X)
 s(mark(X)) -> s(X)
 s(active(X)) -> s(X)
 take(mark(X1),X2) -> take(X1,X2)
 take(X1,mark(X2)) -> take(X1,X2)
 take(active(X1),X2) -> take(X1,X2)
 take(X1,active(X2)) -> take(X1,X2)
 zip(mark(X1),X2) -> zip(X1,X2)
 zip(X1,mark(X2)) -> zip(X1,X2)
 zip(active(X1),X2) -> zip(X1,X2)
 zip(X1,active(X2)) -> zip(X1,X2)
 pair(mark(X1),X2) -> pair(X1,X2)
 pair(X1,mark(X2)) -> pair(X1,X2)
 pair(active(X1),X2) -> pair(X1,X2)
 pair(X1,active(X2)) -> pair(X1,X2)
 tail(mark(X)) -> tail(X)
 tail(active(X)) -> tail(X)
 repItems(mark(X)) -> repItems(X)
 repItems(active(X)) -> repItems(X)

Proof:
 Open