YES Problem: rec[even_0][1](0()) -> True() rec[even_0][1](S(0())) -> False() rec[even_0][1](S(S(x2))) -> rec[even_0][1](x2) main(x1) -> rec[even_0][1](x1) Proof: Matrix Interpretation Processor: dim=3 interpretation: [1 0 1] [main](x0) = [0 0 1]x0 [1 0 0] , [0] [False] = [0] [0], [1 0 0] [0] [S](x0) = [0 0 1]x0 + [0] [0 1 0] [1], [0] [True] = [0] [0], [1 0 1] [rec[even_0][1]](x0) = [0 0 0]x0 [0 0 0] , [0] [0] = [0] [1] orientation: [1] [0] rec[even_0][1](0()) = [0] >= [0] = True() [0] [0] [1] [0] rec[even_0][1](S(0())) = [0] >= [0] = False() [0] [0] [1 0 1] [1] [1 0 1] rec[even_0][1](S(S(x2))) = [0 0 0]x2 + [0] >= [0 0 0]x2 = rec[even_0][1](x2) [0 0 0] [0] [0 0 0] [1 0 1] [1 0 1] main(x1) = [0 0 1]x1 >= [0 0 0]x1 = rec[even_0][1](x1) [1 0 0] [0 0 0] problem: main(x1) -> rec[even_0][1](x1) Matrix Interpretation Processor: dim=3 interpretation: [1 0 0] [1] [main](x0) = [0 0 0]x0 + [0] [0 0 1] [0], [1 0 0] [rec[even_0][1]](x0) = [0 0 0]x0 [0 0 0] orientation: [1 0 0] [1] [1 0 0] main(x1) = [0 0 0]x1 + [0] >= [0 0 0]x1 = rec[even_0][1](x1) [0 0 1] [0] [0 0 0] problem: Qed