The two-row constraints realization problem

✍ Scribed by S.S. Al-Fedaghi

• Book ID: 103930326
• Publisher: Elsevier Science
• Year: 1987
• Tongue: English
• Weight: 562 KB
• Volume: 14
• Category: Article
• ISSN: 0898-1221
• DOI: 10.1016/0898-1221(87)90150-7

✦ Synopsis

Al~raet--Let R(X) be a table with m columns and n rows, where X is the set of columns. A 0-1 matrix T(X) is assoeiatecl with R(X) as follows. T(X) has m columns and (2 ~) rows. Let ui[Asl denotes the entry at column A t in ith row of R(X). Similarly, t~ [Ag] denotes the entry at column A x in the ith row of T(X).

A mapping is defined between each two rows {u, uj} in R(X) and a row tf in T(X) such that tAAs] = 1 if u~[Az] = uj[As]; otherwise tf[A,] = 0. The two-row constraints realization problem deals with conditions under which there exists a table R(X) that corresponds to a given 0-1 matrix T(X). The solution to this problem and its application in the area of the theory of relational database, are discussed in this paper.