YES

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

Proof:
 DP Processor:
  DPs:
   f#(f(a(),x),a()) -> f#(a(),a())
   f#(f(a(),x),a()) -> f#(x,f(a(),a()))
   f#(f(a(),x),a()) -> f#(f(x,f(a(),a())),a())
   f#(f(a(),x),a()) -> f#(f(f(x,f(a(),a())),a()),a())
  TRS:
   f(f(a(),x),a()) -> f(f(f(x,f(a(),a())),a()),a())
  EDG Processor:
   DPs:
    f#(f(a(),x),a()) -> f#(a(),a())
    f#(f(a(),x),a()) -> f#(x,f(a(),a()))
    f#(f(a(),x),a()) -> f#(f(x,f(a(),a())),a())
    f#(f(a(),x),a()) -> f#(f(f(x,f(a(),a())),a()),a())
   TRS:
    f(f(a(),x),a()) -> f(f(f(x,f(a(),a())),a()),a())
   graph:
    f#(f(a(),x),a()) -> f#(f(x,f(a(),a())),a()) ->
    f#(f(a(),x),a()) -> f#(a(),a())
    f#(f(a(),x),a()) -> f#(f(x,f(a(),a())),a()) ->
    f#(f(a(),x),a()) -> f#(x,f(a(),a()))
    f#(f(a(),x),a()) -> f#(f(x,f(a(),a())),a()) ->
    f#(f(a(),x),a()) -> f#(f(x,f(a(),a())),a())
    f#(f(a(),x),a()) -> f#(f(x,f(a(),a())),a()) ->
    f#(f(a(),x),a()) -> f#(f(f(x,f(a(),a())),a()),a())
   SCC Processor:
    #sccs: 1
    #rules: 1
    #arcs: 4/16
    DPs:
     f#(f(a(),x),a()) -> f#(f(x,f(a(),a())),a())
    TRS:
     f(f(a(),x),a()) -> f(f(f(x,f(a(),a())),a()),a())
    Bounds Processor:
     bound: 0
     enrichment: match
     automaton:
      final states: {6,1}
      transitions:
       f30() -> 4*
       f{#,0}(5,2) -> 1*
       f0(3,3) -> 5*
       f0(4,3) -> 5*
       f0(5,2) -> 7*
       f0(7,2) -> 6*
       f0(2,2) -> 3*
       a0() -> 2*
       6 -> 7*
     problem:
      DPs:
       
      TRS:
       f(f(a(),x),a()) -> f(f(f(x,f(a(),a())),a()),a())
     Qed