Re: A Logical Model for Lists as Relations

From: Jay Dee <ais01479_at_aeneas.net>
Date: Fri, 12 May 2006 02:08:21 GMT
Message-ID: <p6S8g.23863$YI5.1629@tornado.ohiordc.rr.com>

JOG wrote:
> vc wrote:
>

>>I am sorry but the 'bunch' vs. set juxtaposition just does not make any
>>obvious sense.  As soon as you talk about a 'bunch', 'herd', 'pack' of
>>'set',  the intuition is the same: a collection of some elements.

>
> A set isn't the same as the other concepts you list, at least as they
> are used in common language.

That's right. That's why different terms are used. Unfortunately, words in common language don't share common meanings.

 > A set with nothing in it still exists and
> it has its own properties, specifically membership and cardinality.
> Bunches and herds do not. While an empty set is still a set, a bunch of
> bananas with no bananas in it is no bunch at all - same with a herd, a
> deck of cards, a forest of trees, etc. These aggregates are called
> fusions, and are merely a pluralization of their components.

And that's probably part of another serviceable manner of discussing these concepts.

>>It's not important whether or not you use the pretty curly brackets.

>
> Well, there's a mathematical field called Mereology that argues the
> exact opposite. I realise this may be a subtle distinction, and at a
> complete tangent to the current discussion, but it may be of interest
> to the OP.

Just so the point isn't lost: the braces and brackets in sets and lists aren't mere punctuation; they're operators. The element and item union operators comma and semicolon - are the same, but the set union and list catenation operators are different -- because they have different operands. Received on Thu May 11 2006 - 21:08:21 CDT