NO

1 decompositions
 #0 -----------
   1: b() -> a()
   2: b() -> c()
   3: b() -> h(h(c(),a()),f(f(b())))
   4: a() -> f(a())
   5: b() -> h(a(),a())

unjoinable peak
    f(a())
*<- b() ->*
    c()