Re: Is a function a relation?
From: Cimode <cimode_at_hotmail.com>
Date: Mon, 29 Jun 2009 08:01:06 -0700 (PDT)
Message-ID: <9babe7bb-ee8c-4db2-abc6-2ee2cfc6e78b_at_c9g2000yqm.googlegroups.com>
Date: Mon, 29 Jun 2009 08:01:06 -0700 (PDT)
Message-ID: <9babe7bb-ee8c-4db2-abc6-2ee2cfc6e78b_at_c9g2000yqm.googlegroups.com>
<<
Given a relation type (i.e. schema), there are a number (possibly
infinite) of relation values that conform to that type. The type and
the values of that type are all abstract and carry almost no
information. >>
The cardinality of un-ary relation subtype can *not* exceed the
cardinality of the relation supertype. That is a constraint imposed
by how a relation is defined.
Received on Mon Jun 29 2009 - 17:01:06 CEST