YES

Problem:
 f(a(),f(x,a())) -> f(a(),f(f(f(a(),a()),a()),x))

Proof:
 DP Processor:
  DPs:
   f#(a(),f(x,a())) -> f#(a(),a())
   f#(a(),f(x,a())) -> f#(f(a(),a()),a())
   f#(a(),f(x,a())) -> f#(f(f(a(),a()),a()),x)
   f#(a(),f(x,a())) -> f#(a(),f(f(f(a(),a()),a()),x))
  TRS:
   f(a(),f(x,a())) -> f(a(),f(f(f(a(),a()),a()),x))
  EDG Processor:
   DPs:
    f#(a(),f(x,a())) -> f#(a(),a())
    f#(a(),f(x,a())) -> f#(f(a(),a()),a())
    f#(a(),f(x,a())) -> f#(f(f(a(),a()),a()),x)
    f#(a(),f(x,a())) -> f#(a(),f(f(f(a(),a()),a()),x))
   TRS:
    f(a(),f(x,a())) -> f(a(),f(f(f(a(),a()),a()),x))
   graph:
    f#(a(),f(x,a())) -> f#(a(),f(f(f(a(),a()),a()),x)) ->
    f#(a(),f(x,a())) -> f#(a(),a())
    f#(a(),f(x,a())) -> f#(a(),f(f(f(a(),a()),a()),x)) ->
    f#(a(),f(x,a())) -> f#(f(a(),a()),a())
    f#(a(),f(x,a())) -> f#(a(),f(f(f(a(),a()),a()),x)) ->
    f#(a(),f(x,a())) -> f#(f(f(a(),a()),a()),x)
    f#(a(),f(x,a())) -> f#(a(),f(f(f(a(),a()),a()),x)) ->
    f#(a(),f(x,a())) -> f#(a(),f(f(f(a(),a()),a()),x))
   SCC Processor:
    #sccs: 1
    #rules: 1
    #arcs: 4/16
    DPs:
     f#(a(),f(x,a())) -> f#(a(),f(f(f(a(),a()),a()),x))
    TRS:
     f(a(),f(x,a())) -> f(a(),f(f(f(a(),a()),a()),x))
    Usable Rule Processor:
     DPs:
      f#(a(),f(x,a())) -> f#(a(),f(f(f(a(),a()),a()),x))
     TRS:
      
     Bounds Processor:
      bound: 1
      enrichment: match
      automaton:
       final states: {5}
       transitions:
        f{#,1}(10,13) -> 5*
        a1() -> 10*
        f1(11,10) -> 12*
        f1(10,10) -> 11*
        f1(12,4) -> 13*
        f1(12,12) -> 13*
        f{#,0}(4,4) -> 5*
        a0() -> 4*
        f0(4,4) -> 4*
      problem:
       DPs:
        
       TRS:
        
      Qed