TRS: { f(x, y, z) -> g(x, y, z), g(0(), 1(), x) -> f(x, x, x)} POP* + Boolean Semantic Labelling: Normal positions: pi(f_sl=0) = [1,2,3], pi(g_sl=0) = [1] Safe positions: pi(f_sl=1) = [1,2,3], pi(g_sl=1) = [1,2,3], pi(g_sl=0) = [2,3] Precedence: f_sl=0 > g_sl=0, g_sl=0 > f_sl=1, f_sl=1 > g_sl=1 empty Interpretation: g^(3): 000 | 0 001 | 0 010 | 0 011 | 0 100 | 0 101 | 0 110 | 0 111 | 0 f^(3): 000 | 0 001 | 0 010 | 0 011 | 0 100 | 0 101 | 0 110 | 0 111 | 0 0^(0): | 1 1^(0): | 0 Labelling: g^(3): 000 | 1 001 | 0 010 | 0 011 | 0 100 | 0 101 | 0 110 | 0 111 | 1 f^(3): 000 | 1 001 | 0 010 | 0 011 | 0 100 | 0 101 | 0 110 | 0 111 | 1 0^(0): | 0 1^(0): | 0 Labelled predicative System: { f_sl=1(;x,y,z) -> g_sl=1(;x,y,z), f_sl=0(x,y,z;) -> g_sl=0(x;y,z), f_sl=0(x,y,z;) -> g_sl=0(x;y,z), f_sl=0(x,y,z;) -> g_sl=0(x;y,z), f_sl=0(x,y,z;) -> g_sl=0(x;y,z), f_sl=0(x,y,z;) -> g_sl=0(x;y,z), f_sl=0(x,y,z;) -> g_sl=0(x;y,z), f_sl=1(;x,y,z) -> g_sl=1(;x,y,z), g_sl=0(0_sl=0();1_sl=0(),x) -> f_sl=1(;x,x,x), g_sl=0(0_sl=0();1_sl=0(),x) -> f_sl=1(;x,x,x)} Qed