(VAR x y )
(RULES 
        a(a(b(b(x)))) -> b(b(b(a(a(a(x))))))
        a(c(x)) -> c(a(x))
        c(b(x)) -> b(c(x))
        dup(A'(a(b(b(x))))) -> collapse(A'(a(x)), A'(a(x)))
        collapse(x, y) -> dup(x)
        collapse(x, y) -> dup(y)
        
)