NO

1 decompositions
 #1 -----------
   1: b(b(b(x1))) -> a(a(a(x1)))
   2: a(a(a(x2))) -> b(a(b(x2)))

unjoinable peak
    b(b(a(b(x1))))
*<- b(b(b(b(x1)))) ->*
    b(a(b(b(x1))))