Yaos millionairesproblemYaos millionairesproblem(YMP)and set-inclusion problem(SIP)are two well known secure two-party computation(STC)problems,in recent decades,many solutions of them were proposed Li et al.proposed a symmetric cryptographic solution to SIP and,by using it as a building block,constructed a symmetric cryptographic solution to YMP(Information Sciences,2008).In this paper,by constructing two counterexamples,it is shown that their solution to SIP is imperfect,i.e.,sometimes,a wrong result will be exported after a correct execution,this implies that their solution to YMP is also imperfect.In addition,a new solution to SIP is proposed based on the additively homomorphic property of Goldwasser-Micali public key cryptosystem.