BEGIN:VCALENDAR VERSION:2.0 PRODID:researchseminars.org CALSCALE:GREGORIAN X-WR-CALNAME:researchseminars.org BEGIN:VEVENT SUMMARY:Viatcheslav Kharlamov (University of Strasbourg) DTSTART:20211028T140000Z DTEND:20211028T150000Z DTSTAMP:20260423T040047Z UID:ZAG/159 DESCRIPTION:Title: Ne w examples of surgery invariant counts in real algebraic geometry\nby Viatcheslav Kharlamov (University of Strasbourg) as part of ZAG (Zoom Alge braic Geometry) seminar\n\n\nAbstract\nInitial Welschinger invariants\, as well as their various generalizations\, are very sensitive\, in general \ , to a change of topology of the underlying real structure. However\, it w as soon noticed that some natural combinations of them have a stronger inv ariance property (remaining also non-trivial in many interesting cases)\, the property that I call "surgery invariance": for a given complex defor mation class of a variety\, they no more depend on a chosen real structure . The starting example is the signed count of real lines on cubic surf aces in accordance with B.~Segre's division of such lines in 2 kinds\, hy perbolic and elliptic. It is this example that originated a discovery of similar counts on higher dimensional hypersurfaces and complete intersect ions\, and served as one of the impulses for a development of an integer valued real Schubert calculus. In this talk (based on a work in progress\, joint with Sergey Finashin) I intend to discuss extending of the above cu bic surface example in a bit different direction: from lines on a cubic su rface to lines\, and even higher degree rational curves\, on other del Pez zo surfaces.\n LOCATION:https://researchseminars.org/talk/ZAG/159/ END:VEVENT END:VCALENDAR