Theorem Proving and Database Querying

By Sergei Savchenko

Dr. Dobb's Journal August 1998

(a)
(c>'1')A = c e : 2 2 : 3 3 :
(b)
A= c e : 1 1 : 1 2 : 2 2 : 3 3 :
B= x y : 1 9 : 2 8 : 4 9 :
<A[cx]B>= c e y : 1 1 9 : 1 2 9 : 2 2 8 :
(c) 
(c>'1')<A[cx]B>= c e y : 2 2 8 :

Example 1: (a) Finding the tuples of A; (b) joining the relations A and B along fields c and x; (c) combining (a) and (b).

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