NO

1 decompositions
 #1 -----------
   1: f(g(f(x1))) -> g(f(g(x1)))
   2: f(c()) -> c()
   3: g(c()) -> c()

unjoinable peak
    f(g(g(f(g(x1)))))
*<- f(g(f(g(f(x1))))) ->*
    g(f(g(g(f(x1)))))