摘要
Thisarticleisbasedonthenotionsofacongruenceofasemigroupandthep-lowerandp-upperapproximationsofanonemptysubsetofasemigroup,discussingsomepropertiesoftheproductofthesetwosubsetsaccordingtothepropertiesofsomeespecialsinglesubsetssuchassubsemigroupsandideals,thentherigorousproofwasgiven.Thustheroughtheoryinsemigroupsarecompletedandperfected.
出版日期
2004年03月13日（中国Betway体育网页登陆平台首次上网日期，不代表论文的发表时间）
