insert to projection

From: paul c <>
Date: Fri, 04 Sep 2009 16:58:11 GMT
Message-ID: <DGbom.42669$Db2.5159_at_edtnps83>

Why do implementation languages not allow this? Surely not for logical reasons? We can delete from projection because NOT Pa implies NOT Pab, eg., <NOT> R{a} -> <NOT> R{a,b}. Logically, we can insert to projections because Pab implies Pa. Isn't the problem really a language deficiency? Received on Fri Sep 04 2009 - 11:58:11 CDT

Original text of this message