Re: Notions of Type

From: paul c <toledobythesea_at_oohay.ac>
Date: Sat, 19 Aug 2006 19:40:00 GMT
Message-ID: <kOJFg.434699$IK3.170187@pd7tw1no>

Marshall wrote:
> paul c wrote:

>> Marshall wrote:
>>> ...

> Yeah, sorta by analogy with boolean algebra. That was actually
> a pretty interesting result they got. I didn't feel like it was an
> endpoint result, though, for a few reasons. It still has the
> only-sorta-algebraic REMOVE in it. It brings up negation, which
> can be problematic. They also didn't analyze the algebraic
> properties as fully as was necessary; I believe I recall
> Vadim pointing out that their algebra lacks absorbtion, an
> important property.

Thanks, absorption seems useful for implementations, I'll ponder that.

In the D&D context, I have wondered once or twice whether a version of de Morgan tailored for the lattice-style union is possible. The TA-style union intrigued me because of how it handled projection which made me wonder could D&D algebra be adapted to allow a common-column union, without throwing negation out the window. I suppose if that is possible, then my complaint about David C's suggestion of empty relations and a binary project might have been wrong.

Not sure why I think about this, maybe it's just that my preference for the narrow view makes me find great comfort in the CWA, ie., it's just a psychological preference.

p Received on Sat Aug 19 2006 - 14:40:00 CDT