(GOAL COMPLEXITY) (STARTTERM (FUNCTIONSYMBOLS f0)) (VAR A B C D) (RULES f1(A, B, C, D) -> Com_1(f1(A - 1, B, C, D)) [ A >= 1 ] f1(A, B, C, D) -> Com_1(f1(A + B, B + C, C + D, D - 1)) [ A >= 1 ] f0(A, B, C, D) -> Com_1(f1(A, B, C, D)) )