21. The structures below are organized by how many sets are involved, and how many binary operations are used. 22. A semigroup has an " associative " binary operation , but might not have an identity element. 23. Binary operations sometimes use prefix or ( probably more often ) postfix notation, both of which dispense with parentheses.24. The homomorphic image of a quasigroup defined with a single binary operation , however, need not be a quasigroup. 25. Algebraically, a lattice is a set with two associative, commutative idempotent binary operations linked by corresponding absorption laws. 26. These flags can be tested using binary operations or with the Enum type's builtin'HasFlag'method. 27. If I know what " set " and " binary operation " is, then I have all I need. 28. It must be remarked that this binary operation on the class of classes of groups is neither associative nor commutative. 29. By doing this it is possible to perform binary operations on enumerations, thus treating enumeration values as sets of flags. 30. The most commonly studied structures, however, usually involve only one or two sets and one or two binary operations .
