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
    w: (Int, Int, Int, Int, Int) -> Unit
  Rules
    w(!n, !p1, !p2, !p, !i) -> v(!n, !p, !p1, !p, +(!i, 1)) [not(<(!p, !p1))]
    w(!n, !p1, !p2, !p, !i) -> return(-2) [<(!p, !p1)]
    v(!n, !p1, !p2, !p, !i) -> return(!p) [not(<(!i, !n))]
    v(!n, !p1, !p2, !p, !i) -> w(!n, !p1, !p2, +(!p1, !p2), !i) [<(!i, !n)]
    u(!n, !p1, !p2, !p, !i) -> v(!n, !p1, !p2, !p, 1) [and(and(not(<(!n, 0)), not(!n = 0)), not(!n = 1))]
    u(!n, !p1, !p2, !p, !i) -> return(1) [and(and(not(<(!n, 0)), not(!n = 0)), !n = 1)]
    u(!n, !p1, !p2, !p, !i) -> return(0) [and(not(<(!n, 0)), !n = 0)]
    u(!n, !p1, !p2, !p, !i) -> return(-1) [<(!n, 0)]
    fastfib(!x) -> u(!x, 1, 0, !rnd1, !rnd2)
No termination info given.

Elapsed Time:  66.56 ms