Sibirskie Èlektronnye Matematicheskie Izvestiya [Siberian Electronic Mathematical Reports]
RUS  ENG    JOURNALS   PEOPLE   ORGANISATIONS   CONFERENCES   SEMINARS   VIDEO LIBRARY   PACKAGE AMSBIB  
General information
Latest issue
Archive
Impact factor

Search papers
Search references

RSS
Latest issue
Current issues
Archive issues
What is RSS



Sib. Èlektron. Mat. Izv.:
Year:
Volume:
Issue:
Page:
Find






Personal entry:
Login:
Password:
Save password
Enter
Forgotten password?
Register


Sibirskie Èlektronnye Matematicheskie Izvestiya [Siberian Electronic Mathematical Reports], 2020, Volume 17, Pages 1270–1279
DOI: https://doi.org/10.33048/semi.2020.17.093
(Mi semr1287)
 

Discrete mathematics and mathematical cybernetics

The nonexistence small $Q$-polynomial graphs of type (III)

A. A. Makhneva, M. M. Isakovab, A. A. Tokbaevab

a N.N. Krasovskii Institute of Mathematics and Mechanics of the Ural Branch of the Russian Academy of Sciences, 16, S.Kovalevskaya str., Yekaterinburg, 620990, Russia
b Kabardino-Balkarian State University named after H.M. Berbekov, 175, Chernyshevsky str., Nalchik, 360004, Russia
References:
Abstract: I.N. Belousov, A.A. Makhnev and M.S. Nirova found the description of $Q$-polynomial distance-regular graphs $\Gamma$ of diameter 3 such that $\Gamma_2$ and $\Gamma_3$ are strongly regular. Such graph has intersection array $\{t(c_2+1)+a_3,tc_2,a_3+1;1,c_2,t(c_2+1)\}$ and $(c_2+1)=a_3(a_3+1)/(t^2-a_3-1)$. $Q$-polynomial graph $\Gamma$ is the graph of type (I), if $a_3$ is devided by $c_2+1$, graph of type (II), if $a_3+1$ is devided by $c_2+1$, graph of type (III), if $a_3$ and $a_3+1$ does not devided by $c_2+1$.
In this paper it is proved that graph of type (III) with $t\le 6$ has intersection array $\{14,10,3;1,5,12\}$, $\{69,56,10;1,14,60\}$, $\{74,54,15;1, 9,60\}$, $\{87,66,16;1,11,72\}$, $\{119,100,15;1,20,105\}$ or $\{188,162,21;1, 27,168\}$.
Further it is proved that graphs of type (III) with intersection array $\{14,10,3;1,5,12\}$, $\{87,66,16;1,11,72\}$ and $\{188,162,21;1,27,168\}$ do not exist.
Keywords: distance-regular graph, $Q$-polynomial graph, triple intersection numbers.
Funding agency Grant number
Ministry of Education and Science of the Russian Federation 02.A03.21.0006
Received July 19, 2020, published September 7, 2020
Bibliographic databases:
Document Type: Article
UDC: 519.17
MSC: 05C25
Language: Russian
Citation: A. A. Makhnev, M. M. Isakova, A. A. Tokbaeva, “The nonexistence small $Q$-polynomial graphs of type (III)”, Sib. Èlektron. Mat. Izv., 17 (2020), 1270–1279
Citation in format AMSBIB
\Bibitem{MakIsaTok20}
\by A.~A.~Makhnev, M.~M.~Isakova, A.~A.~Tokbaeva
\paper The nonexistence small $Q$-polynomial graphs of type (III)
\jour Sib. \`Elektron. Mat. Izv.
\yr 2020
\vol 17
\pages 1270--1279
\mathnet{http://mi.mathnet.ru/semr1287}
\crossref{https://doi.org/10.33048/semi.2020.17.093}
Linking options:
  • https://www.mathnet.ru/eng/semr1287
  • https://www.mathnet.ru/eng/semr/v17/p1270
  • Citing articles in Google Scholar: Russian citations, English citations
    Related articles in Google Scholar: Russian articles, English articles
    Statistics & downloads:
    Abstract page:195
    Full-text PDF :30
    References:25
     
      Contact us:
     Terms of Use  Registration to the website  Logotypes © Steklov Mathematical Institute RAS, 2024