YES

Problem:
 dfib(s(s(x)),y) -> dfib(s(x),dfib(x,y))

Proof:
 DP Processor:
  DPs:
   dfib#(s(s(x)),y) -> dfib#(x,y)
   dfib#(s(s(x)),y) -> dfib#(s(x),dfib(x,y))
  TRS:
   dfib(s(s(x)),y) -> dfib(s(x),dfib(x,y))
  Subterm Criterion Processor:
   simple projection:
    pi(dfib#) = 0
   problem:
    DPs:
     
    TRS:
     dfib(s(s(x)),y) -> dfib(s(x),dfib(x,y))
   Qed