let R be the TRS under consideration

splitAt(s(_1),cons(_2)) -> u(splitAt(_1,_3)) is in elim_R(R)
let l be the left-hand side and r be the right-hand side of this rule
let p = 0.1
let theta = {_3/splitAt(s(_1),cons(_2))}
let theta' = {}
we have r|p = _3 and
theta'(theta(l)) = theta(r|p)
so, theta(l) = splitAt(s(_1),cons(_2)) is non-terminating w.r.t. R

Termination disproved by the forward process
proof stopped at iteration i=0, depth k=0
1 rule(s) generated