MAYBE
LCTRS
  Theories
    Core, Ints
  Sorts
    Unit
  Signature
    fastfib: Int -> Unit
    return: Int -> Unit
    u: (Int, Int, Int, Int) -> Unit
    v: (Int, Int, Int, Int) -> Unit
  Rules
    v(!x, !i, !p, !q) -> return(!q) [not(<(!i, !x))]
    v(!x, !i, !p, !q) -> v(!x, +(!i, 1), +(!p, !q), !p) [<(!i, !x)]
    u(!x, !i, !p, !q) -> v(!x, 1, !p, !q) [and(not(!x = 0), not(!x = 1))]
    u(!x, !i, !p, !q) -> return(1) [and(not(!x = 0), !x = 1)]
    u(!x, !i, !p, !q) -> return(0) [!x = 0]
    fastfib(!x) -> u(!x, !rnd, 1, 0)
No termination info given.

Elapsed Time:  47.31 ms