NO

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

unjoinable peak
    h(h(c(),b()),f(f(h(h(c(),c()),c()))))
*<- h(h(b(),b()),f(f(h(h(c(),c()),c())))) ->*
    c()