YES

Problem:
 app(nil(),xs) -> nil()
 app(cons(x,xs),ys) -> cons(x,app(xs,ys))

Proof:
 DP Processor:
  DPs:
   app#(cons(x,xs),ys) -> app#(xs,ys)
  TRS:
   app(nil(),xs) -> nil()
   app(cons(x,xs),ys) -> cons(x,app(xs,ys))
  CDG Processor:
   DPs:
    app#(cons(x,xs),ys) -> app#(xs,ys)
   TRS:
    app(nil(),xs) -> nil()
    app(cons(x,xs),ys) -> cons(x,app(xs,ys))
   graph:
    
   Qed