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

CP_S(R):

CR(S):
see below.

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

CPS'(R):

CP(R):