(VAR x y )
(STRATEGY INNERMOST)
(RULES 
        f(x,a(b(c(y)))) -> f(b(c(a(b(x)))),y)
        f(a(x),y) -> f(x,a(y))
        f(b(x),y) -> f(x,b(y))
        f(c(x),y) -> f(x,c(y))
        
)