let R be the TRS under consideration

f(s(a),s(b),_1) -> f(_1,_1,_1) is in elim_R(R)
let r0 be the right-hand side of this rule
p0 = 0 is a position in r0
we have r0|p0 = _1
cons(_2,_3) -> _2 is in R
let l'0 be the left-hand side of this rule
theta0 = {_1/cons(_2,_3)} is a mgu of r0|p0 and l'0

==> f(s(a),s(b),cons(_1,_2)) -> f(_1,cons(_1,_2),cons(_1,_2)) is in EU_R^1
let r1 be the right-hand side of this rule
p1 = 1 is a position in r1
we have r1|p1 = cons(_1,_2)
cons(_3,_4) -> _4 is in R
let l'1 be the left-hand side of this rule
theta1 = {_1/_3, _2/_4} is a mgu of r1|p1 and l'1

==> f(s(a),s(b),cons(_1,_2)) -> f(_1,_2,cons(_1,_2)) is in EU_R^2
let l be the left-hand side and r be the right-hand side of this rule
let p = epsilon
let theta = {_1/s(a), _2/s(b)}
let theta' = {}
we have r|p = f(_1,_2,cons(_1,_2)) and
theta'(theta(l)) = theta(r|p)
so, theta(l) = f(s(a),s(b),cons(s(a),s(b))) is non-terminating w.r.t. R

Termination disproved by the forward process
proof stopped at iteration i=2, depth k=2
9 rule(s) generated