Re: Notions of Type
From: Vadim Tropashko <vadimtro_invalid_at_yahoo.com>
Date: 19 Aug 2006 16:06:35 -0700
Message-ID: <1156028795.797500.133510_at_75g2000cwc.googlegroups.com>
Date: 19 Aug 2006 16:06:35 -0700
Message-ID: <1156028795.797500.133510_at_75g2000cwc.googlegroups.com>
paul c wrote:
> D&D claim their algebra can also
> be reduced to two operators as well, take your choice, NAND and REMOVE
> or NOR and REMOVE.
I doubt it. Can you please supply reference, or better yet write expressions for all 6 classic relational operators in terms of NOR and REMOVE? One reason for a doubt is that Relational Algebra has one operator that still can't be expressed in terms of union and join -- the set difference. Therefore, if D&D can reduce all 6 operations to just 2, then it's quite an achievement. Received on Sun Aug 20 2006 - 01:06:35 CEST