We consider termination of the LCTRS with only rule scheme Calc: Signature: f :: Int -> Int -> Int -> A Rules: f(x, y, z) -> f(x, x + 1, x - 1) | y < z The system is accessible function passing by a sort ordering that equates all sorts. We start by computing the initial DP problem D1 = (P1, R, f, c), where: P1. (1) f#(x, y, z) => f#(x, x + 1, x - 1) | y < z ***** No progress could be made on DP problem D1 = (P1, R, f, c).