MAYBE
LCTRS
  Theories
    Core, Ints
  Sorts
    Unit
  Signature
    fastfib: Int -> Unit
    return: Int -> Unit
    u: (Int, Int, Int, Int, Int) -> Unit
    v: (Int, Int, Int, Int, Int) -> Unit
  Rules
    v(!n, !fi, !fp, !fn, !i) -> return(!fi) [not(<(!i, !n))]
    v(!n, !fi, !fp, !fn, !i) -> v(!n, +(!fi, !fp), !fi, +(!fi, !fp), +(!i, 1)) [<(!i, !n)]
    u(!n, !fi, !fp, !fn, !i) -> v(!n, !fi, !fp, !fn, 1) [not(<=(!n, 0))]
    u(!n, !fi, !fp, !fn, !i) -> return(0) [<=(!n, 0)]
    fastfib(!n) -> u(!n, 1, 0, !rnd1, !rnd2)
No termination info given.

Elapsed Time:  41.90 ms