On incidence algebras and directed graphs

The incidence algebra I(X,ℝ) of a locally finite poset (X,≤) has been defined and studied by Spiegel and O'Donnell (1997). A poset (V,≤) has a directed graph (Gv,≤) representing it. Conversely, any directed graph G without any cycle, multiple edges, and loops is represented by a partially order...

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Main Author: Ancykutty Joseph
Format: Article
Language:English
Published: Wiley 2002-01-01
Series:International Journal of Mathematics and Mathematical Sciences
Online Access:http://dx.doi.org/10.1155/S0161171202007925
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author Ancykutty Joseph
author_facet Ancykutty Joseph
author_sort Ancykutty Joseph
collection DOAJ
description The incidence algebra I(X,ℝ) of a locally finite poset (X,≤) has been defined and studied by Spiegel and O'Donnell (1997). A poset (V,≤) has a directed graph (Gv,≤) representing it. Conversely, any directed graph G without any cycle, multiple edges, and loops is represented by a partially ordered set VG. So in this paper, we define an incidence algebra I(G,ℤ) for (G,≤) over ℤ, the ring of integers, by I(G,ℤ)={fi,fi*:V×V→ℤ} where fi(u,v) denotes the number of directed paths of length i from u to v and fi*(u,v)=−fi(u,v). When G is finite of order n, I(G,ℤ) is isomorphic to a subring of Mn(ℤ). Principal ideals Iv of (V,≤) induce the subdigraphs 〈Iv〉 which are the principal ideals ℐv of (Gv,≤). They generate the ideals I(ℐv,ℤ) of I(G,ℤ). These results are extended to the incidence algebra of the digraph representing a locally finite weak poset both bounded and unbounded.
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spelling doaj-art-f463f475b9d84cf289083a76d75d2f062025-02-03T01:11:40ZengWileyInternational Journal of Mathematics and Mathematical Sciences0161-17121687-04252002-01-0131530130510.1155/S0161171202007925On incidence algebras and directed graphsAncykutty Joseph0Department of Mathematics, St. Dominic's College, Kanjirapally 686512, Kerala, IndiaThe incidence algebra I(X,ℝ) of a locally finite poset (X,≤) has been defined and studied by Spiegel and O'Donnell (1997). A poset (V,≤) has a directed graph (Gv,≤) representing it. Conversely, any directed graph G without any cycle, multiple edges, and loops is represented by a partially ordered set VG. So in this paper, we define an incidence algebra I(G,ℤ) for (G,≤) over ℤ, the ring of integers, by I(G,ℤ)={fi,fi*:V×V→ℤ} where fi(u,v) denotes the number of directed paths of length i from u to v and fi*(u,v)=−fi(u,v). When G is finite of order n, I(G,ℤ) is isomorphic to a subring of Mn(ℤ). Principal ideals Iv of (V,≤) induce the subdigraphs 〈Iv〉 which are the principal ideals ℐv of (Gv,≤). They generate the ideals I(ℐv,ℤ) of I(G,ℤ). These results are extended to the incidence algebra of the digraph representing a locally finite weak poset both bounded and unbounded.http://dx.doi.org/10.1155/S0161171202007925
spellingShingle Ancykutty Joseph
On incidence algebras and directed graphs
International Journal of Mathematics and Mathematical Sciences
title On incidence algebras and directed graphs
title_full On incidence algebras and directed graphs
title_fullStr On incidence algebras and directed graphs
title_full_unstemmed On incidence algebras and directed graphs
title_short On incidence algebras and directed graphs
title_sort on incidence algebras and directed graphs
url http://dx.doi.org/10.1155/S0161171202007925
work_keys_str_mv AT ancykuttyjoseph onincidencealgebrasanddirectedgraphs