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<div align="center"><big><b><big>Welcome to the 2025 Fall
talks of ODTÜ-Bilkent Algebraic Geometry Seminars</big></b></big><b><br>
</b></div>
<div align="center"><i>since 2000</i><br>
</div>
<div align="center"><b><b>=================================================================</b></b><br>
<br>
This week the <a
href="http://www.bilkent.edu.tr/~sertoz/agseminar.htm"
target="_blank" moz-do-not-send="true">ODTÜ-Bilkent
Algebraic Geometry Seminar</a> is <b>online</b><br>
<br>
<i><font color="#ff00ff">This talk will begin at <u><b>15:40</b></u><u> (GMT+3)</u></font></i><br>
<a
href="https://www.timeanddate.com/worldclock/fixedtime.html?msg=ODT%C3%9C-Bilkent+Algebraic+Geometry+Seminar&iso=20251017T1540&p1=19&ah=1"
target="_blank" moz-do-not-send="true">Please check
your time difference between Ankara and your city here</a><br>
<b>=================================================================<br>
<br>
</b></div>
<div align="center">
<div align="center"><img
src="cid:part1.3fuujiOR.zjp0NkfR@bilkent.edu.tr"
alt="" width="443" height="564" class=""></div>
</div>
<div align="center"><br>
</div>
<div align="center"><i>Jean-Leon Gerome (1824-1904)<br>
</i></div>
<div align="center"><i><br>
</i></div>
<div align="center"><i><br>
</i>
<div align="left">
<div align="left"><b><b><font color="#ff0000">Speaker:
</font>Bayram Tekin</b></b></div>
<b><b><font color="#ff0000"><font color="#000000"> </font></font></b></b><b><b><font
color="#ff0000">Affiliation:<i> </i></font></b></b><i><b>Bilkent</b></i></div>
<div align="left"><b><b><i><br>
</i></b></b></div>
<div align="left"><b><b><font color="#ff0000"> Title: <font
color="#000000">A rank-4 tensor Riemann would
have loved plus spinor-techniques in
differential geometry<br>
</font></font></b><b><font color="#ff0000"><font
color="#000000"><br>
</font></font></b></b></div>
</div>
<div align="left"><b><b><font color="#ff0000">Abstract: </font></b></b>I
would like to discuss two topics that have proved very
useful in the parts of differential geometry used in
General Relativity and other theories of gravity. The
first one is the introduction of a divergence-free rank
4 tensor which was hiding in plain sight up until our
paper ( <a moz-do-not-send="true"
href="https://journals.aps.org/prd/abstract/10.1103/PhysRevD.99.044026">Phys.
Rev. D 99 (2019) 4, 044026</a>). The second topic will
include formulating differential geometry in terms of
Weyl spinors which are fundamental representations of
SL(2,C).<b><b><font color="#ff0000"><br>
</font></b></b></div>
<div align="left"><br>
</div>
<div align="left"><font color="#ff0000"><font
color="#000000"><b><font color="#ff0000">Date:<font
color="#000000"> 17 October 2025, Friday</font></font></b></font></font></div>
<div align="left"><font color="#ff0000"><font
color="#000000"><b><font color="#ff0000">Time: </font>15:40 <i>(GMT+3)</i></b><br>
<b><font color="#ff0000">Place: </font></b><font
color="#ff0000"><font color="#000000"><b>Zoom</b></font></font></font></font></div>
<blockquote>
<p><i><b>Participants who have registered will receive
the Zoom link via email one day before the
seminar.</b></i></p>
<p><i><b>If you registered for a previous talk in this
series, there's no need to register again—you'll
automatically receive the link for this session.</b></i></p>
<p><i><b moz-do-not-send="true"
href="mailto:sertoz@bilkent.edu.tr">If you haven't
registered yet, please contact <a
href="mailto:sertoz@bilkent.edu.tr"
class="moz-txt-link-freetext"
moz-do-not-send="true">sertoz@bilkent.edu.tr</a>
to be added to the mailing list.</b></i></p>
</blockquote>
<div align="left">You are most cordially invited to
attend.</div>
<div align="left"><br>
</div>
<div align="left">Ali Sinan Sertöz</div>
<div align="left"><br>
</div>
<div align="center">
<div align="center"><b><font color="#0080c0"><i><b><font
color="#0080c0"><i>This seminar series is
organized by a joint team from ODTÜ and
Bilkent<br>
<br>
Alexander Degtyarev (Bilkent)<br>
Ali Sinan Sertöz (Bilkent) contact person<br>
Ali Ulaş Özgür Kişisel (ODTÜ)<br>
Yıldıray Ozan (ODTÜ)<br>
</i></font></b></i></font></b></div>
<div align="left"><br>
</div>
</div>
<div align="left"><font size="1"><i>(PS: <a
href="mailto:sertoz@gmail.com?cc=sertoz%40bilkent.edu.tr&subject=Unsubscribe&body=Please%20remove%20this%20address%20from%20the%20announcement%20list%20of%20ODT%C3%9C-Bilkent%20Algebraic%20Geometry%20Seminars."
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without changing anything</a>.)</i></font> </div>
<hr>
<pre cols="72">----------------------------------------------------------------------------
Ali Sinan Sertöz
Bilkent University, Department of Mathematics, 06800 Ankara, Türkiye
Office: (90)-(312) - 290 1490
Department: (90)-(312) - 266 4377
e-mail: <a href="mailto:sertoz@bilkent.edu.tr" target="_blank"
class="gmail-moz-txt-link-freetext moz-txt-link-freetext"
moz-do-not-send="true">sertoz@bilkent.edu.tr</a>
Web: <a href="http://sertoz.bilkent.edu.tr" target="_blank"
moz-do-not-send="true">sertoz.bilkent.edu.tr</a>
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