Displaying similar documents to “Some Remarks on Reproductive Solutions”

From two- to four-valued logic

Chris Brink (1993)

Banach Center Publications

Similarity:

The purpose of this note is to show that a known and natural four-valued logic co-exists with classical two-valued logic in the familiar context of truth tables. The tool required is the power construction.

Repetitions and permutations of columns in the semijoin algebra

Dirk Leinders, Jan Van Den Bussche (2009)

RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications

Similarity:

Codd defined the relational algebra [E.F. Codd, Communications of the ACM 13 (1970) 377–387; E.F. Codd, Relational completeness of data base sublanguages, in Data Base Systems, R. Rustin, Ed., Prentice-Hall (1972) 65–98] as the algebra with operations projection, join, restriction, union and difference. His projection operator can drop, permute and repeat columns of a relation. This permuting and repeating of columns does not really add expressive power to the relational algebra. Indeed,...