YES(?,PRIMREC) We are left with following problem, upon which TcT provides the certificate YES(?,PRIMREC). 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(?,PRIMREC) The input was oriented with the instance of'multiset path order' as induced by the precedence not > xor, not > and, true > xor, true > and, implies > xor, implies > and, or > xor, or > and, = > xor, = > and, not ~ true, not ~ implies, not ~ or, not ~ =, xor ~ and, true ~ implies, true ~ or, true ~ =, implies ~ or, implies ~ =, or ~ = . Hurray, we answered YES(?,PRIMREC)