NO

1 decompositions
 #0 -----------
   1: a(a(x)) -> b(b(b(x)))
   2: b(b(b(b(x)))) -> a(a(a(x)))

unjoinable peak
    a(b(b(b(x))))
*<- a(a(a(x))) ->*
    b(b(b(a(x))))