let R be the TRS under consideration

f(a,b,_1) -> f(_1,_1,_1) is in elim_R(R)
let l0 be the left-hand side of this rule
p0 = 0 is a position in l0
we have l0|p0 = a
c -> a is in R
let r'0 be the right-hand side of this rule
theta0 = {} is a mgu of l0|p0 and r'0

==> f(c,b,_1) -> f(_1,_1,_1) is in EU_R^1
let l1 be the left-hand side of this rule
p1 = 1 is a position in l1
we have l1|p1 = b
c -> b is in R
let r'1 be the right-hand side of this rule
theta1 = {} is a mgu of l1|p1 and r'1

==> f(c,c,_1) -> f(_1,_1,_1) 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/c}
let theta' = {}
we have r|p = f(_1,_1,_1) and
theta'(theta(l)) = theta(r|p)
so, theta(l) = f(c,c,c) is non-terminating w.r.t. R

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