(VAR x1 )
(RULES 
        a(a(a(a(x1)))) -> a(a(b(b(b(b(b(b(x1))))))))
        b(b(a(a(x1)))) -> b(b(b(b(c(c(x1))))))
        a(a(b(b(b(b(c(c(x1)))))))) -> a(a(a(a(a(a(b(b(x1))))))))
        
)