MAYBE

Problem:
 app(app(map(),f),nil()) -> nil()
 app(app(map(),f),app(app(cons(),x),xs)) -> app(app(cons(),app(f,x)),app(app(map(),f),xs))
 app(flatten(),app(app(node(),x),xs)) ->
 app(app(cons(),x),app(concat(),app(app(map(),flatten()),xs)))
 app(concat(),nil()) -> nil()
 app(concat(),app(app(cons(),x),xs)) -> app(app(append(),x),app(concat(),xs))
 app(app(append(),nil()),xs) -> xs
 app(app(append(),app(app(cons(),x),xs)),ys) -> app(app(cons(),x),app(app(append(),xs),ys))

Proof:
 DP Processor:
  DPs:
   app#(app(map(),f),app(app(cons(),x),xs)) -> app#(app(map(),f),xs)
   app#(app(map(),f),app(app(cons(),x),xs)) -> app#(f,x)
   app#(app(map(),f),app(app(cons(),x),xs)) -> app#(cons(),app(f,x))
   app#(app(map(),f),app(app(cons(),x),xs)) -> app#(app(cons(),app(f,x)),app(app(map(),f),xs))
   app#(flatten(),app(app(node(),x),xs)) -> app#(map(),flatten())
   app#(flatten(),app(app(node(),x),xs)) -> app#(app(map(),flatten()),xs)
   app#(flatten(),app(app(node(),x),xs)) -> app#(concat(),app(app(map(),flatten()),xs))
   app#(flatten(),app(app(node(),x),xs)) -> app#(cons(),x)
   app#(flatten(),app(app(node(),x),xs)) ->
   app#(app(cons(),x),app(concat(),app(app(map(),flatten()),xs)))
   app#(concat(),app(app(cons(),x),xs)) -> app#(concat(),xs)
   app#(concat(),app(app(cons(),x),xs)) -> app#(append(),x)
   app#(concat(),app(app(cons(),x),xs)) -> app#(app(append(),x),app(concat(),xs))
   app#(app(append(),app(app(cons(),x),xs)),ys) -> app#(append(),xs)
   app#(app(append(),app(app(cons(),x),xs)),ys) -> app#(app(append(),xs),ys)
   app#(app(append(),app(app(cons(),x),xs)),ys) -> app#(app(cons(),x),app(app(append(),xs),ys))
  TRS:
   app(app(map(),f),nil()) -> nil()
   app(app(map(),f),app(app(cons(),x),xs)) -> app(app(cons(),app(f,x)),app(app(map(),f),xs))
   app(flatten(),app(app(node(),x),xs)) ->
   app(app(cons(),x),app(concat(),app(app(map(),flatten()),xs)))
   app(concat(),nil()) -> nil()
   app(concat(),app(app(cons(),x),xs)) -> app(app(append(),x),app(concat(),xs))
   app(app(append(),nil()),xs) -> xs
   app(app(append(),app(app(cons(),x),xs)),ys) -> app(app(cons(),x),app(app(append(),xs),ys))
  Open