(VAR X X1 X2)
(RULES 
a__h(X) -> a__g(mark(X),X)
a__g(a,X) -> a__f(b,X)
a__f(X,X) -> a__h(a__a)
a__a -> b
mark(h(X)) -> a__h(mark(X))
mark(g(X1,X2)) -> a__g(mark(X1),X2)
mark(a) -> a__a
mark(f(X1,X2)) -> a__f(mark(X1),X2)
mark(b) -> b
a__h(X) -> h(X)
a__g(X1,X2) -> g(X1,X2)
a__a -> a
a__f(X1,X2) -> f(X1,X2)
)