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2. Relational algebra - Wikipedia

   en.wikipedia.org/wiki/Relational_algebra

   The relational algebra uses set union, set difference, and Cartesian product from set theory, and adds additional constraints to these operators to create new ones.. For set union and set difference, the two relations involved must be union-compatible—that is, the two relations must have the same set of attributes.

3. Relation algebra - Wikipedia

   en.wikipedia.org/wiki/Relation_algebra

   A relation algebra (L, ∧, ∨, −, 0, 1, •, I, ˘) is an algebraic structure equipped with the Boolean operations of conjunction x∧y, disjunction x∨y, and negation x −, the Boolean constants 0 and 1, the relational operations of composition x•y and converse x˘, and the relational constant I, such that these operations and constants satisfy certain equations constituting an ...

4. Composition of relations - Wikipedia

   en.wikipedia.org/wiki/Composition_of_relations

   Another form of composition of relations, which applies to general -place relations for , is the join operation of relational algebra. The usual composition of two binary relations as defined here can be obtained by taking their join, leading to a ternary relation, followed by a projection that removes the middle component.

5. Relation (mathematics) - Wikipedia

   en.wikipedia.org/wiki/Relation_(mathematics)

   Since relations are sets, they can be manipulated using set operations, including union, intersection, and complementation, leading to the algebra of sets. Furthermore, the calculus of relations includes the operations of taking the converse and composing relations. [7] [8] [9]

6. Selection (relational algebra) - Wikipedia

   en.wikipedia.org/wiki/Selection_(relational_algebra)

   In relational algebra, a selection (sometimes called a restriction in reference to E.F. Codd's 1970 paper [1] and not, contrary to a popular belief, to avoid confusion with SQL's use of SELECT, since Codd's article predates the existence of SQL) is a unary operation that denotes a subset of a relation.

7. NYT ‘Connections’ Hints and Answers Today, Thursday ... - AOL

   www.aol.com/nyt-connections-hints-answers-today...

   Get ready for all of today's NYT 'Connections’ hints and answers for #592 on Thursday, January 23, 2025. Today's NYT Connections puzzle for Thursday, January 23, 2025The New York Times