YES(?,O(1)) We are left with following problem, upon which TcT provides the certificate YES(?,O(1)). Strict Trs: { not(x) -> xor(x, true()) , implies(x, y) -> xor(and(x, y), xor(x, true())) , or(x, y) -> xor(and(x, y), xor(x, y)) , =(x, y) -> xor(x, xor(y, true())) } Obligation: innermost runtime complexity Answer: YES(?,O(1)) The input was oriented with the instance of 'Small Polynomial Path Order (PS)' as induced by the safe mapping safe(not) = {1}, safe(xor) = {1, 2}, safe(true) = {}, safe(implies) = {}, safe(and) = {1, 2}, safe(or) = {}, safe(=) = {1} and precedence not > implies, or > implies, = > implies, not ~ or, not ~ =, or ~ = . Following symbols are considered recursive: {} The recursion depth is 0. For your convenience, here are the satisfied ordering constraints: not(; x) > xor(; x, true()) implies(x, y;) > xor(; and(; x, y), xor(; x, true())) or(x, y;) > xor(; and(; x, y), xor(; x, y)) =(y; x) > xor(; x, xor(; y, true())) Hurray, we answered YES(?,O(1))