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<title>Cohomology in algebra, geometry, physics and statistics</title>
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Wednesday, 11 March 2026 - 13:30 to 14:30 <br />
Place: Institute of Mathematics of ASCR, Žitná 25, Praha 1, ZOOM meeting
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Speaker: Russell Avdek, Institut de Mathématiques de Jussieu, Sorbonne Université<br />
Title: Numerical invariants of contact manifolds and their divisors
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Abstract <br />
<p><span style="color: rgb(0, 0, 0);">I will introduce an invariant E(K) of codim=2 contact submanifolds K of a contact manifold (of any dimension), generalizing the self-linking number SL(K) of transverse links in the contact 3-sphere. Extending the observation that SL(L)=1 mod 2 for knots, modular properties E(K) are intimately related to the divisibilities of certain Chern numbers. A generalization of Gompf's d3 invariant of contact 3-manifolds is also defined and used to uncover surprising properties of E(K). These tools provide novel information about Milnor numbers of complex hypersurface singularities.</span></p><p>------------------------------------------------------------------------</p><p><br></p><p class="ql-align-justify"><span style="color: rgb(34, 34, 34); background-color: rgb(255, 255, 255);">We shall open the ZOOM meeting at 13.15 for (virtual) coffee and close ZOOM at 15.00</span></p><p class="ql-align-justify"><br></p><p class="ql-align-justify"><span style="color: rgb(34, 34, 34); background-color: rgb(255, 255, 255);">Join Zoom Meeting</span></p><p class="ql-align-justify"><br></p><p class="ql-align-justify"><a href="https://cesnet.zoom.us/j/99598413922?pwd=YXNFbk50aVhleXhWSGtISFViLytRUT09" rel="noopener noreferrer" target="_blank" style="background-color: rgb(255, 255, 255); color: rgb(17, 85, 204);">https://cesnet.zoom.us/j/99598413922?pwd=YXNFbk50aVhleXhWSGtISFViLytRUT09</a></p><p class="ql-align-justify"><br></p><p class="ql-align-justify"><span style="color: rgb(34, 34, 34); background-color: rgb(255, 255, 255);">Meeting ID:99598413922</span></p><p class="ql-align-justify"><span style="color: rgb(34, 34, 34); background-color: rgb(255, 255, 255);">Passcode:Galois</span></p><p>--------------------------------------------------------------------------------------------------------------------------------</p><p>On Wednesday March 18 Hông Vân Lê shall give a talk on <a href="https://www.math.cas.cz/index.php/events/event/4151" rel="noopener noreferrer" target="_blank"> Minimal Unital Cyclic C∞ -Algebras and the Real and Rational Homotopy Types of Closed Manifolds</a></p>
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For more information see the seminar web page at <br />
https://www.math.cas.cz/index.php/events/seminar/16
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Cohomology in algebra, geometry, physics and statistics mailing list <br />
phk_seminar@math.cas.cz <br />
https://list.math.cas.cz/listinfo/phk_seminar@math.cas.cz
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