---- CR(R cup S)
---- [Klein and Hirokawa, 2012]
R:
f(a()) -> b()
f(a()) -> f(c())
a() -> d()
f(d()) -> b()
f(c()) -> b()
d() -> c()
S:

CP_S(R):
b() -> f(c())
f(c()) -> b()
f(d()) -> b()
f(d()) -> f(c())
f(c()) -> b()
CR(S):
see below.

---- CR(R)
---- [Hirokawa and Middeldorp, 2011]
R:

CPS'(R):

CP(R):