# Podelski/Rybalchenko: Transition Invariants (LICS 2004)
(VAR x y)
(RULES
eval_1(x, y) -> eval_2(x, 1) :|: x >= 0
eval_2(x, y) -> eval_2(x, 2 * y) :|: x >= 0 && y > 0 && x > y
eval_2(x, y) -> eval_1(x - 1, y) :|: x >= 0 && y > 0 && y >= x
)