YES

Problem:
 a__zeros() -> cons(0(),zeros())
 a__tail(cons(X,XS)) -> mark(XS)
 mark(zeros()) -> a__zeros()
 mark(tail(X)) -> a__tail(mark(X))
 mark(cons(X1,X2)) -> cons(mark(X1),X2)
 mark(0()) -> 0()
 a__zeros() -> zeros()
 a__tail(X) -> tail(X)

Proof:
 DP Processor:
  DPs:
   a__tail#(cons(X,XS)) -> mark#(XS)
   mark#(zeros()) -> a__zeros#()
   mark#(tail(X)) -> mark#(X)
   mark#(tail(X)) -> a__tail#(mark(X))
   mark#(cons(X1,X2)) -> mark#(X1)
  TRS:
   a__zeros() -> cons(0(),zeros())
   a__tail(cons(X,XS)) -> mark(XS)
   mark(zeros()) -> a__zeros()
   mark(tail(X)) -> a__tail(mark(X))
   mark(cons(X1,X2)) -> cons(mark(X1),X2)
   mark(0()) -> 0()
   a__zeros() -> zeros()
   a__tail(X) -> tail(X)
  TDG Processor:
   DPs:
    a__tail#(cons(X,XS)) -> mark#(XS)
    mark#(zeros()) -> a__zeros#()
    mark#(tail(X)) -> mark#(X)
    mark#(tail(X)) -> a__tail#(mark(X))
    mark#(cons(X1,X2)) -> mark#(X1)
   TRS:
    a__zeros() -> cons(0(),zeros())
    a__tail(cons(X,XS)) -> mark(XS)
    mark(zeros()) -> a__zeros()
    mark(tail(X)) -> a__tail(mark(X))
    mark(cons(X1,X2)) -> cons(mark(X1),X2)
    mark(0()) -> 0()
    a__zeros() -> zeros()
    a__tail(X) -> tail(X)
   graph:
    mark#(tail(X)) -> mark#(X) -> mark#(cons(X1,X2)) -> mark#(X1)
    mark#(tail(X)) -> mark#(X) -> mark#(tail(X)) -> a__tail#(mark(X))
    mark#(tail(X)) -> mark#(X) -> mark#(tail(X)) -> mark#(X)
    mark#(tail(X)) -> mark#(X) -> mark#(zeros()) -> a__zeros#()
    mark#(tail(X)) -> a__tail#(mark(X)) ->
    a__tail#(cons(X,XS)) -> mark#(XS)
    mark#(cons(X1,X2)) -> mark#(X1) ->
    mark#(cons(X1,X2)) -> mark#(X1)
    mark#(cons(X1,X2)) -> mark#(X1) ->
    mark#(tail(X)) -> a__tail#(mark(X))
    mark#(cons(X1,X2)) -> mark#(X1) -> mark#(tail(X)) -> mark#(X)
    mark#(cons(X1,X2)) -> mark#(X1) ->
    mark#(zeros()) -> a__zeros#()
    a__tail#(cons(X,XS)) -> mark#(XS) ->
    mark#(cons(X1,X2)) -> mark#(X1)
    a__tail#(cons(X,XS)) -> mark#(XS) ->
    mark#(tail(X)) -> a__tail#(mark(X))
    a__tail#(cons(X,XS)) -> mark#(XS) ->
    mark#(tail(X)) -> mark#(X)
    a__tail#(cons(X,XS)) -> mark#(XS) -> mark#(zeros()) -> a__zeros#()
   SCC Processor:
    #sccs: 1
    #rules: 4
    #arcs: 13/25
    DPs:
     mark#(tail(X)) -> mark#(X)
     mark#(tail(X)) -> a__tail#(mark(X))
     a__tail#(cons(X,XS)) -> mark#(XS)
     mark#(cons(X1,X2)) -> mark#(X1)
    TRS:
     a__zeros() -> cons(0(),zeros())
     a__tail(cons(X,XS)) -> mark(XS)
     mark(zeros()) -> a__zeros()
     mark(tail(X)) -> a__tail(mark(X))
     mark(cons(X1,X2)) -> cons(mark(X1),X2)
     mark(0()) -> 0()
     a__zeros() -> zeros()
     a__tail(X) -> tail(X)
    CDG Processor:
     DPs:
      mark#(tail(X)) -> mark#(X)
      mark#(tail(X)) -> a__tail#(mark(X))
      a__tail#(cons(X,XS)) -> mark#(XS)
      mark#(cons(X1,X2)) -> mark#(X1)
     TRS:
      a__zeros() -> cons(0(),zeros())
      a__tail(cons(X,XS)) -> mark(XS)
      mark(zeros()) -> a__zeros()
      mark(tail(X)) -> a__tail(mark(X))
      mark(cons(X1,X2)) -> cons(mark(X1),X2)
      mark(0()) -> 0()
      a__zeros() -> zeros()
      a__tail(X) -> tail(X)
     graph:
      mark#(tail(X)) -> a__tail#(mark(X)) -> a__tail#(cons(X,XS)) -> mark#(XS)
     SCC Processor:
      #sccs: 0
      #rules: 0
      #arcs: 1/16