# Re: How is this collection called?

Date: Tue, 30 Mar 2004 10:14:40 -0500

Message-ID: <c4c2rc$2hfd8f$1_at_ID-114862.news.uni-berlin.de>

PLEASE don't do homework for someone...

"Michael Mendelsohn" <keine.Werbung.1300_at_michael.mendelsohn.de> wrote in
message news:406940AB.883662FF_at_michael.mendelsohn.de...

*> Mikito Harakiri schrieb:
*

> > Let '*' be binary aggregation operator.

*>
**> > Then, sets obey the following laws:
**> > 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
**>
**> > What collection type meets
**> > a*a!=a
**> > a*b!=b*a
**> > a*(b*c)!=(a*b)*c
**> >
**> > ?
**>
**> Stack?
**> x * y := pop elements off stack x and push them on y
**>
**> Example:
**> a=(1,2), b=(3,4), c=(5,6)
**> a*b = (1,2)*(3,4) = (2)*(1,3,4) = (2,1,3,4)
**> b*c = (3,4)*(5,6) = (4,3,5,6)
**>
**> (a*b)*c = (2,1,3,4) * (5,6) = (4,3,1,2,5,6)
**> a*(b*c) = (1,2) * (4,3,5,6) = (2,1,4,3,5,6)
**>
**> Michael
**>
**> --
**> Feel the stare of my burning hamster and stop smoking!
*

Received on Tue Mar 30 2004 - 17:14:40 CEST