| Popis: |
Conjunctive table algebras are introduced and axiomatically characterized. A conjunctive table algebra is a variant of SPJR algebra (a weaker form of relational algebra), which corresponds to conjunctive queries with equality. The table operations relate to logical operations (e.g. column deletion corresponds to existential quantification). This enables a connection between database theory and algebraic logic, particularly cylindric algebras. A comparison shows which cylindric algebra axioms hold in conjunctive table algebras, which ones are modified, and which ones hold in addition. |
