Cardinality of relation with empty set of attributes is 1
From: Aloha Kakuikanu <aloha.kakuikanu_at_yahoo.com>
Date: 2 Oct 2006 11:38:17 -0700
Message-ID: <1159814297.566570.15720_at_m73g2000cwd.googlegroups.com>
Proof:
MVFD with empty antecedent, for example
{X,Y,Z} doesn't really change the relation, it follows that the other
relation in the MVFD decompostition should have cardianlity 1. Received on Mon Oct 02 2006 - 20:38:17 CEST
Date: 2 Oct 2006 11:38:17 -0700
Message-ID: <1159814297.566570.15720_at_m73g2000cwd.googlegroups.com>
Proof:
MVFD with empty antecedent, for example
{} -> {X} | {Y,Z}
claims that cardinality of the XYZ relation is the product of cardinalities of its projection onto the sets X and YZ of attributes.
Take {X} to be an empty set, then:
{} -> {} | {X,Y,Z}
{X,Y,Z} doesn't really change the relation, it follows that the other
relation in the MVFD decompostition should have cardianlity 1. Received on Mon Oct 02 2006 - 20:38:17 CEST