---- CR(R)
---- [Hirokawa and Middeldorp, 2011]
R:
f(g(x)) -> f(h(x,x))
g(a()) -> g(g(a()))
h(a(),a()) -> g(g(a()))
CPS'(R):
f(g(a())) -> f(g(g(a())))
f(g(a())) -> f(h(a(),a()))
CP(R):
f(g(g(a()))) -> f(h(a(),a()))