User mojtaba jazaeri - MathOverflow most recent 30 from http://mathoverflow.net 2013-05-24T01:59:31Z http://mathoverflow.net/feeds/user/31179 http://www.creativecommons.org/licenses/by-nc/2.5/rdf http://mathoverflow.net/questions/122723/the-number-of-specific-structure The number of specific structure Mojtaba Jazaeri 2013-02-23T14:11:30Z 2013-02-24T06:19:41Z <p>What is the number of families of \$4t+1\$ subsets of order \$2t\$ of the set \${1,2, \ldots ,p}\$, where \$p\$ is a prime number which is equal to \$4t+1\$ and the order of intersection of each pair of the subsets is \$t\$ or \$t-1\$ and each subset has \$t\$-intersection with \$2t\$ subsets and \$t-1\$-intersection with the other \$2t\$ subsets?</p> http://mathoverflow.net/questions/120857/the-number-of-non-isomorphic-strongly-regular-graphs-on-n-vertices The number of non-isomorphic strongly regular graphs on n vertices Mojtaba Jazaeri 2013-02-05T13:46:03Z 2013-02-05T14:32:15Z <p>What is the number of strongly regular graphs on \$n\$ vertices? or at least how many non-isomorphic strongly regular graphs can exist?</p> http://mathoverflow.net/questions/122723/the-number-of-specific-structure Comment by Mojtaba Jazaeri Mojtaba Jazaeri 2013-02-23T14:12:30Z 2013-02-23T14:12:30Z Thank you every one who answer to this question. http://mathoverflow.net/questions/120857/the-number-of-non-isomorphic-strongly-regular-graphs-on-n-vertices/120861#120861 Comment by Mojtaba Jazaeri Mojtaba Jazaeri 2013-02-09T18:52:37Z 2013-02-09T18:52:37Z As we know, every strongly regular graph over prime number of vertices is a conference graph and Paley graph is a conference graph and the following sentence due to Willem H. HAEMERS: For v = 5, 9, 13 and 17, the Paley graph is the only one with the given parameters. If \$v \geq 25\$, other graphs with the same parameters exist. in the following paper: Matrices for graphs, designs and codes Why this sentence is true? if this sentence is true, then there are at least 2 non-isomorphic strongly regular graphs on prime number of vertices \$p&gt;25\$. http://mathoverflow.net/questions/120857/the-number-of-non-isomorphic-strongly-regular-graphs-on-n-vertices Comment by Mojtaba Jazaeri Mojtaba Jazaeri 2013-02-05T17:54:39Z 2013-02-05T17:54:39Z Thank you very much Professor Chris Godsil and professor Aaron Meyerowitz. http://mathoverflow.net/questions/120857/the-number-of-non-isomorphic-strongly-regular-graphs-on-n-vertices Comment by Mojtaba Jazaeri Mojtaba Jazaeri 2013-02-05T13:54:15Z 2013-02-05T13:54:15Z Thank you for every one who answer to the question.