MAYBE

Problem:
 digits() -> d(0())
 d(x) -> if(le(x,s(s(s(s(s(s(s(s(s(0())))))))))),x)
 if(true(),x) -> cons(x,d(s(x)))
 if(false(),x) -> nil()
 le(0(),y) -> true()
 le(s(x),0()) -> false()
 le(s(x),s(y)) -> le(x,y)

Proof:
 DP Processor:
  DPs:
   digits#() -> d#(0())
   d#(x) -> le#(x,s(s(s(s(s(s(s(s(s(0()))))))))))
   d#(x) -> if#(le(x,s(s(s(s(s(s(s(s(s(0())))))))))),x)
   if#(true(),x) -> d#(s(x))
   le#(s(x),s(y)) -> le#(x,y)
  TRS:
   digits() -> d(0())
   d(x) -> if(le(x,s(s(s(s(s(s(s(s(s(0())))))))))),x)
   if(true(),x) -> cons(x,d(s(x)))
   if(false(),x) -> nil()
   le(0(),y) -> true()
   le(s(x),0()) -> false()
   le(s(x),s(y)) -> le(x,y)
  Usable Rule Processor:
   DPs:
    digits#() -> d#(0())
    d#(x) -> le#(x,s(s(s(s(s(s(s(s(s(0()))))))))))
    d#(x) -> if#(le(x,s(s(s(s(s(s(s(s(s(0())))))))))),x)
    if#(true(),x) -> d#(s(x))
    le#(s(x),s(y)) -> le#(x,y)
   TRS:
    le(0(),y) -> true()
    le(s(x),s(y)) -> le(x,y)
    le(s(x),0()) -> false()
   Open