Výsledky vyhledávání - "Miguel Angel Fiol"

Spectra and eigenspaces of arbitrary lifts of graphs

Autor: Miguel Angel Fiol, Cristina Dalfó, Sona Pavlikova, Jozef Širáň

Publikováno v: Repositorio Abierto de la UdL
Universitad de Lleida
UPCommons. Portal del coneixement obert de la UPC
Universitat Politècnica de Catalunya (UPC)
Recercat. Dipósit de la Recerca de Catalunya
instname
Journal of Algebraic Combinatorics

This is a post-peer-review, pre-copyedit version of an article published in Journal of algebraic combinatorics. The final authenticated version is available online at: http://dx.doi.org/10.1007/s10801-021-01049-3 We describe, in a very explicit way,

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::b48e76515c902f1aac64188c77dcc4b6
https://doi.org/10.1007/s10801-021-01049-3

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Bipartite biregular Moore graphs

Autor: Nacho López, Cristina Dalfó, Miguel Angel Fiol, Gabriela Araujo-Pardo

Publikováno v: Repositorio Abierto de la UdL
Universitad de Lleida
UPCommons. Portal del coneixement obert de la UPC
Universitat Politècnica de Catalunya (UPC)
Discrete Mathematics

A bipartite graph $G=(V,E)$ with $V=V_1\cup V_2$ is biregular if all the vertices of a stable set $V_i$ have the same degree $r_i$ for $i=1,2$. In this paper, we give an improved new Moore bound for an infinite family of such graphs with odd diameter

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::9dae3c3a336ad67676f8c045cc52026b
https://doi.org/10.1016/j.disc.2021.112582

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On d-Fibonacci digraphs

Autor: Miguel Angel Fiol, Cristina Dalfó

Publikováno v: Electronic Journal of Graph Theory and Applications
Electronic Journal of Graph Theory and Applications, Vol 9, Iss 2, Pp 527-538 (2021)
Repositorio Abierto de la UdL
Universitad de Lleida
UPCommons. Portal del coneixement obert de la UPC
Universitat Politècnica de Catalunya (UPC)

The d-Fibonacci digraphs F(d, k), introduced here, have the number of vertices following some generalized Fibonacci-like sequences. They can be defined both as digraphs on alphabets and as iterated line digraphs. Here we study some of their nice prop

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::744b45d5d2638bd5619839cad3266c9c
https://hdl.handle.net/10459.1/72285

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New results for the Mondrian art problem

Autor: Nacho López, Miguel Angel Fiol, Cristina Dalfó

Publikováno v: UPCommons. Portal del coneixement obert de la UPC
Universitat Politècnica de Catalunya (UPC)
Discrete Applied Mathematics
Recercat. Dipósit de la Recerca de Catalunya
instname
Repositorio Abierto de la UdL
Universitad de Lleida
Recercat: Dipósit de la Recerca de Catalunya
Varias* (Consorci de Biblioteques Universitáries de Catalunya, Centre de Serveis Científics i Acadèmics de Catalunya)

The Mondrian problem consists of dissecting a square of side length n ∈ N into non-congruent rectangles with natural length sides such that the difference d(n) between the largest and the smallest areas of the rectangles partitioning the square is

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::141f1ffa3a19e531746aaa1379c4c609
http://hdl.handle.net/2117/354903

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A general method to obtain the spectrum and local spectra of a graph from its regular partitions

Autor: C. Dalfó, Miguel Angel Fiol

Publikováno v: Repositorio Abierto de la UdL
Universitad de Lleida
Recercat. Dipósit de la Recerca de Catalunya
instname
UPCommons. Portal del coneixement obert de la UPC
Universitat Politècnica de Catalunya (UPC)
Linear Algebra and its Applications
Recercat: Dipósit de la Recerca de Catalunya
Varias* (Consorci de Biblioteques Universitáries de Catalunya, Centre de Serveis Científics i Acadèmics de Catalunya)

It is well known that, in general, part of the spectrum of a graph can be obtained from the adjacency matrix of its quotient graph given by a regular partition. In this paper, a method that gives all the spectrum, and also the local spectra, of a gra

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::78513a231380d4aafbf958f2c0777882
http://hdl.handle.net/10459.1/70126

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On the k-independence number of graphs

Autor: Miguel Angel Fiol, Gabriel Coutinho, Aida Abiad

Publikováno v: Discrete Mathematics, 342(10), 2875-2885. Elsevier
UPCommons. Portal del coneixement obert de la UPC
Universitat Politècnica de Catalunya (UPC)
Recercat. Dipósit de la Recerca de Catalunya
instname

© 2019. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/ This paper generalizes and unifies the existing spectral bounds on the k-independence number of a graph, which is t

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https://hdl.handle.net/2117/131577

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The spectra of lifted digraphs

Autor: Jozef Širáň, Cristina Dalfó, Miguel Angel Fiol

We present a method to derive the complete spectrum of the lift Γα of a base digraph Γ , with voltage assignment α on a (finite) group G. The method is based on assigning to Γ a quotient-like matrix whose entries are elements of the group algebr

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http://hdl.handle.net/10459.1/67512

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A Note on the Order of Iterated Line Digraphs

Autor: Cristina Dalfó, Miguel Angel Fiol

Publikováno v: Journal of Graph Theory. 85:395-399

Given a digraph G, we propose a new method to find the recurrence equation for the number of vertices n_k of the k-iterated line digraph L_k(G), for k>= 0, where L_0(G) = G. We obtain this result by using the minimal polynomial of a quotient digraph

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::2045744a5784d4d31fa3846a4c086f43
https://doi.org/10.1002/jgt.22068

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Cospectral digraphs from locally line digraphs

Autor: Miguel Angel Fiol, Cristina Dalfó

Publikováno v: UPCommons. Portal del coneixement obert de la UPC
Universitat Politècnica de Catalunya (UPC)
Recercat. Dipósit de la Recerca de Catalunya
instname
Repositorio Abierto de la UdL
Universitad de Lleida

A digraph Γ =(V, E) is a line digraph when every pair of vertices u, v∈V have either equal or disjoint in-neighborhoods. When this condition only applies for vertices in a given subset (with at least two elements), we say that Γ is a locally line

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https://doi.org/10.1016/j.laa.2016.03.014

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On bipartite-mixed graphs

Autor: Miguel Angel Fiol, Nacho López, Cristina Dalfó

Publikováno v: Recercat. Dipósit de la Recerca de Catalunya
instname
Repositorio Abierto de la UdL
Universitad de Lleida
UPCommons. Portal del coneixement obert de la UPC
Universitat Politècnica de Catalunya (UPC)

This is the peer reviewed version of the following article: Dalfo, C., Fiol, M., López, N. On bipartite-mixed graphs. "Journal of graph theory", 24 Abril 2018, p. 1-9, which has been published in final form at https://onlinelibrary.wiley.com/doi/ful

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::cdf28baf128c443fef9f8663d8c8f92d
https://hdl.handle.net/2117/118347

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