Oracle FAQ Your Portal to the Oracle Knowledge Grid
HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US
 

Home -> Community -> Usenet -> comp.databases.theory -> Re: repeating groups

Re: repeating groups

From: Mikito Harakiri <mikharakiri_nospaum_at_yahoo.com>
Date: 19 Feb 2006 10:31:17 -0800
Message-ID: <1140373877.254904.110990@g44g2000cwa.googlegroups.com>


Marshall Spight wrote:
> I see no reason to add bags. In fact, I'm not even sure I
> believe a bag is an actual data structure. It seems more
> like a traversal strategy on a set. What makes you think
> you need bags?

Here is a snippet from old exchange "how is this collection called":

Let '*' be binary aggregation operator.

Then, sets obey the following laws:

a*a=a
a*b=b*a
a*(b*c)=(a*b)*c


Bags:

a*a!=a
a*b=b*a
a*(b*c)=(a*b)*c


Lists:

a*a!=a
a*b!=b*a
a*(b*c)=(a*b)*c


We see that progression to more complex collection types gives up more and more algebraic properties. Does this explain why colllection based algebras were not so successfull? Received on Sun Feb 19 2006 - 12:31:17 CST

Original text of this message

HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US