1Dipartimento di Matematica, Informatica ed Economia Università degli Studi della Basilicata Viale dell'Ateneo Lucano,10 I-85100 Potenza, Italy. 2Instituto de Matemáticas Campus Juriquilla Universidad Nacional Autónoma de México Juriquilla 76230 Querétaro, México. 3Departament de Matemática Aplicada III Universitat Politècnica de Catalunya Campus Nord, Edifici C2 C/ Jordi Girona 1-3 E-08034 Barcelona, Spain. and Matemáticas Aplicadas y Sistemas Universidad Autónoma Metropolitana unidad de Cuajimalpa Av. Vasco de Quiroga 4871, Col. Santa Fé, Cuajimalpa, México, D.F. 05348, México. 4Departament d'Enginyeria Informàtica i Matemàtiques, Universitat Rovira i Virgili, Av. Paisos Catalans, 26 43007 Tarragona, Spain.
The electronic journal of combinatorics, Tome 22 (2015) no. 3
In this paper, we construct new infinite families of regular graphs of girth 7 of smallest order known so far. Our constructions are based on combinatorial and geometric properties of $(q+1,8)$-cages, for $q$ a prime power. We remove vertices from such cages and add matchings among the vertices of minimum degree to achieve regularity in the new graphs. We obtain $(q+1)$-regular graphs of girth 7 and order $2q^3+q^2+2q$ for each even prime power $q \ge 4$, and of order $2q^3+2q^2-q+1$ for each odd prime power $q\ge 5$. A corrigendum was added to this paper on 21 June 2016.
M. Abreu 
1
;
G. Araujo-Pardo 
2
;
C. Balbuena 
3
;
D. Labbate 
1
;
J. Salas 
4
1
Dipartimento di Matematica,
Informatica ed Economia
Università degli Studi della Basilicata
Viale dell'Ateneo Lucano,10
I-85100 Potenza, Italy.
2
Instituto de Matemáticas
Campus Juriquilla
Universidad Nacional Autónoma de México
Juriquilla 76230
Querétaro, México.
3
Departament de Matemática Aplicada III
Universitat Politècnica de Catalunya
Campus Nord, Edifici C2
C/ Jordi Girona 1-3
E-08034 Barcelona, Spain.
and
Matemáticas Aplicadas y Sistemas
Universidad Autónoma Metropolitana
unidad de Cuajimalpa
Av. Vasco de Quiroga 4871,
Col. Santa Fé, Cuajimalpa,
México, D.F. 05348, México.
4
Departament d'Enginyeria
Informàtica i Matemàtiques,
Universitat Rovira i Virgili,
Av. Paisos Catalans, 26
43007 Tarragona, Spain.
@article{10_37236_4205,
author = {M. Abreu and G. Araujo-Pardo and C. Balbuena and D. Labbate and J. Salas},
title = {Small regular graphs of girth 7},
journal = {The electronic journal of combinatorics},
year = {2015},
volume = {22},
number = {3},
doi = {10.37236/4205},
zbl = {1327.05163},
url = {http://geodesic.mathdoc.fr/articles/10.37236/4205/}
}
TY - JOUR
AU - M. Abreu
AU - G. Araujo-Pardo
AU - C. Balbuena
AU - D. Labbate
AU - J. Salas
TI - Small regular graphs of girth 7
JO - The electronic journal of combinatorics
PY - 2015
VL - 22
IS - 3
UR - http://geodesic.mathdoc.fr/articles/10.37236/4205/
DO - 10.37236/4205
ID - 10_37236_4205
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%0 Journal Article
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%A G. Araujo-Pardo
%A C. Balbuena
%A D. Labbate
%A J. Salas
%T Small regular graphs of girth 7
%J The electronic journal of combinatorics
%D 2015
%V 22
%N 3
%U http://geodesic.mathdoc.fr/articles/10.37236/4205/
%R 10.37236/4205
%F 10_37236_4205
M. Abreu; G. Araujo-Pardo; C. Balbuena; D. Labbate; J. Salas. Small regular graphs of girth 7. The electronic journal of combinatorics, Tome 22 (2015) no. 3. doi: 10.37236/4205