[6538] in s-news-athena
Re: COMBINATIONAL PROBLEM -2
daemon@ATHENA.MIT.EDU (Francoise Gelis)
Tue Feb 28 13:11:05 1995
Date: Tue, 28 Feb 1995 18:24:18 GMT
From: Francoise Gelis <fg@baobab.jouy.inra.fr>
To: dwh@bom.gov.au, s-news@utstat.toronto.edu
The unique number of combinations whose elements do NOT share the same
set is : n1 * n2 * ... * np, where (ni) are the numbers of elements in
each set, and p the number of sets.
In the example, we obtain 3 * 2 * 2 = 12 (12 = 35 - 23 : you have
forgotten 134, 135, 136 and 137 which have elements sharing the same -
first - set).
Francoise Gelis
----------------------------------------------------------------------
INRA Francoise.Gelis@jouy.inra.fr
Laboratoire de Biometrie
78352 Jouy-en-Josas Cedex
France
----------------------------------------------------------------------
Lotto Player asked:
|> COMBINATIONAL PROBLEM -2
|> Can anyone help ?
|> Sorry, my maths background is limited.
|>
|> Yes I am also interested in sets with differing numbers of elements
|>
|> eg
|>
|> set a 1,2,3
|> set b 4,5
|> set c 6,7
|>
|> total elements 1,2,3,4,5,6,7 = 7 elements
|> 3 from 7 = 35 combinations, but several of them have
|> elements which share the same set.
|>
|> I did not quite get the explanation regarding this type
|> of problem when sets have differing numbers of elements.
|>
|> Could somebody provide another example for this type of case.
|> My requirement is to caculate the number of combinations
|> of 3 from 7 who's elements do not share the same set.
|>
|>
|> COMBINATIONS (combos with * have elements sharing the same set. There are 19)
|> 123* 234* 345* 456*
|> 124* 235* 346 457*
|> 125* 236* 347 467*
|> 126* 237* 356 567*
|> 127* 245* 357
|> 134 246 367*
|> 135 247
|> 136 256
|> 137 257
|> 145* 267*
|> 146
|> 147
|> 156
|> 157
|> 167*
