Català   Castellano   English
 Empreu aquest identificador per citar o enllaçar aquest ítem: `http://hdl.handle.net/2117/8048`

Arxiu Descripció MidaFormat
almost-dist-reg(II)(25apr10)8FCC.pdfArticle principal77,5 kBAdobe PDF
Veure/Obrir

 Citació: Dalfo, C. [et al.]. When almost distance-regularity attains distance-regularity. A: 8th French Combinatorial Conference. "8th French Combinatorial Conference". Orsay, París: 2010, p. 99. Títol: When almost distance-regularity attains distance-regularity Autor: Dalfó Simó, Cristina ; Van Dam, Edwin; Fiol Mora, Miquel Àngel ; Garriga Valle, Ernest Data: 2010 Tipus de document: Conference report Resum: Generally speaking, `almost distance-regular graphs' are graphs which share some, but not necessarily all, regularity properties that characterize distance-regular graphs. In this paper we rst propose four basic di erent (but closely related) concepts of almost distance-regularity. In some cases, they coincide with concepts introduced before by other authors, such as walk-regular graphs and partially distance-regular graphs. Here it is always assumed that the diameter D of the graph attains its maximum possible value allowed by its number d+1 of di erent eigenvalues; that is, D = d, as happens in every distance-regular graph. Our study focuses on nding out when almost distance- regularity leads to distance-regularity. In other words, some `economic' (in the sense of minimizing the number of conditions) old and new characterizations of distance- regularity are discussed. For instance, if A0;A1; : : : ;AD and E0;E1; : : : ;Ed denote, respectively, the distance matrices and the idempotents of the graph; and D and A stand for their respective linear spans, any of the two following `dual' conditions su ce: (a) A0;A1;AD 2 A; (b) E0;E1;Ed 2 D. Moreover, other characterizations based on the preintersection parameters, the average intersection numbers and the recurrence coe cients are obtained. In some cases, our results can be also seen as a generalization of the so-called spectral excess theorem for distance-regular graphs. URI: http://hdl.handle.net/2117/8048 Apareix a les col·leccions: COMBGRAF - Combinatòria, Teoria de Grafs i Aplicacions. Ponències/Comunicacions de congressosDepartaments de Matemàtica Aplicada. Ponències/Comunicacions de congressosAltres. Enviament des de DRAC Comparteix:

Aquest ítem (excepte textos i imatges no creats per l'autor) està subjecte a una llicència de Creative Commons Llicència Creative Commons

 Programari DSpace Copyright © 2002-2004 MIT and Hewlett-Packard Comentaris Universitat Politècnica de Catalunya. Servei de Biblioteques, Publicacions i Arxius