Weighted Compositions
Canadian mathematical bulletin, Tome 4 (1961) no. 1, pp. 39-43
Voir la notice de l'article provenant de la source Cambridge
By a composition of a positive integer n is meant a representation of n as a sum of one or more positive integers where the order of the summands is taken into account. Thus for example 4 has the eight compositions 4 = 3 + 1 = 1 +3 = 2 + 2 = 2 + 1 + 1 = 1 + 2 + 1 = 1 + 1 + 2 = 1 + 1 + 1 + 1. Now n can be written in the form 1 + 1 + ... + 1 with n - 1 plus signs. Deletion of any subset of these plus signs breaks n into parts which form a composition of n. Conversely, any composition of n corresponds to a subset of plus signs, so that the number of compositions of n is the number of subsets of a set with n - 1 elements, namely 2n - 1. In this note we obtain a number of generalizations of this rather obvious remark by making use of the notion of a weighted composition and the method of generating series.
Moser, L.; Whitney, E. L. Weighted Compositions. Canadian mathematical bulletin, Tome 4 (1961) no. 1, pp. 39-43. doi: 10.4153/CMB-1961-006-0
@article{10_4153_CMB_1961_006_0,
author = {Moser, L. and Whitney, E. L.},
title = {Weighted {Compositions}},
journal = {Canadian mathematical bulletin},
pages = {39--43},
year = {1961},
volume = {4},
number = {1},
doi = {10.4153/CMB-1961-006-0},
url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-1961-006-0/}
}
Cité par Sources :