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  <title><![CDATA[PhD Defense by Xiaofan Yuan]]></title>
  <body><![CDATA[<p>Xiaofan Yuan<br />
(Advisor: &nbsp;Prof. &nbsp;Xingxing Yu) will defend a doctoral thesis entitled,<br />
Matching Problems in Hypergraphs<br />
On<br />
Thursday, June 9 at 10:00 a.m.<br />
Skiles 006<br />
https://gatech.zoom.us/j/91659544858?pwd=SWZtVG15dGFiWEFXSHR1U0JNbVVBZz09</p>

<p><br />
Abstract<br />
Ku&uml;hn, Osthus, and Treglown and, independently, Khan proved that if H is a 3-uniform hypergraph&nbsp;<br />
with n vertices, where n &isin; 3Z and large, and &delta;₁(H) &gt; &nbsp;ⁿ&minus;&sup1; &nbsp;&minus; 2n/3 &nbsp;, then H contains a perfect</p>

<p><br />
&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;<br />
We show that for n &nbsp; &nbsp; 3Z &nbsp;sufficiently large, &nbsp;if F , . . . , F &nbsp; &nbsp; &nbsp;are 3-uniform hypergraphs&nbsp;<br />
with a common vertex set and &delta;₁(Fi) &gt; (n&minus;1)&minus;(2n/3) for i &isin; [n/3], then {F₁, . . . , Fn/3} admits a&nbsp;<br />
rainbow</p>

<p><br />
&nbsp;&nbsp; &nbsp;<br />
matching, i.e., a matching consisting of one edge from each Fi. &nbsp;This is done by converting the<br />
rainbow matching problem to a perfect matching problem in a special class of uniform hypergraphs.&nbsp;<br />
We also prove that, for any integers k, l with k &ge; 3 and k/2 &lt; l &le; k &minus; 1, there exists a positive&nbsp;<br />
real &micro; such that, for all sufficiently large integers m, n satisfying<br />
n<br />
k<br />
&minus; &micro;n &le; m<br />
&le;<br />
n<br />
k<br />
&minus;<br />
1<br />
l<br />
&nbsp; &nbsp; &nbsp; &nbsp; l<br />
2l &minus; k<br />
,<br />
if H &nbsp;is a k-uniform hypergraph on n &nbsp;vertices and &delta;l(H) &nbsp;&gt;</p>

<p>(n&minus;</p>

<p><br />
) &minus;</p>

<p>) &nbsp; hen H &nbsp;has a</p>

<p><br />
. This improves upon an earlier result of H`an, Person, and Schacht for the range k/2 &nbsp;&lt; l &le; k &minus; 1.&nbsp;<br />
&nbsp;In many cases, our result gives tight bound on &delta;l(H) &nbsp;for near perfect matchings (e.g., &nbsp;when l &nbsp;&ge;&nbsp;<br />
2k/3, &nbsp;n &nbsp;&equiv; r &nbsp;(mod k), &nbsp;0 &nbsp;&le; r &nbsp;&lt; &nbsp;k, &nbsp;and r + l &nbsp;&ge; k, &nbsp;we can take m = &nbsp;n/k &nbsp;&minus; 2).<br />
Committee<br />
&bull; &nbsp;Prof. Anton Bernshteyn - School of Mathematics, Georgia Institute of Technology<br />
&bull; &nbsp;Prof. Hao Huang - Department of Mathematics, National University of Singapore (reader)<br />
&bull; &nbsp;Prof. Santosh Vempala - College of Computing, Georgia Institute of Technology<br />
&bull; &nbsp;Prof. Josephine Yu - School of Mathematics, Georgia Institute of Technology<br />
&bull; &nbsp;Prof. Xingxing Yu - School of Mathematics, Georgia Institute of Technology (advisor)<br />
&nbsp;</p>
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