let R be the TRS under consideration

length1 -> length is in elim_R(R)
let r0 be the right-hand side of this rule
p0 = epsilon is a position in r0
we have r0|p0 = length
length -> s(length1) is in R
let l'0 be the left-hand side of this rule
theta0 = {} is a mgu of r0|p0 and l'0

==> length1 -> s(length1) is in EU_R^1
let l be the left-hand side and r be the right-hand side of this rule
let p = 0
let theta = {}
let theta' = {}
we have r|p = length1 and
theta'(theta(l)) = theta(r|p)
so, theta(l) = length1 is non-terminating w.r.t. R

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