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BEGIN:VEVENT
SUMMARY:Libby Taylor (Stanford University)
DTSTART:20210129T160000Z
DTEND:20210129T170000Z
DTSTAMP:20260422T225718Z
UID:RationalVarieties/1
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/RationalVari
 eties/1/">Derived equivalences of gerbey curves.</a>\nby Libby Taylor (Sta
 nford University) as part of Rational Varieties Seminar (Séminaire Varié
 tés Rationnelles)\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/RationalVarieties/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Igor Rapinchuk (Michigan State University)
DTSTART:20210212T150000Z
DTEND:20210212T160000Z
DTSTAMP:20260422T225718Z
UID:RationalVarieties/2
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/RationalVari
 eties/2/">Algebraic groups with good reduction</a>\nby Igor Rapinchuk (Mic
 higan State University) as part of Rational Varieties Seminar (Séminaire 
 Variétés Rationnelles)\n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/RationalVarieties/2/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Vladimir Mitankin (Leibniz University Hannover)
DTSTART:20210312T133000Z
DTEND:20210312T143000Z
DTSTAMP:20260422T225718Z
UID:RationalVarieties/3
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/RationalVari
 eties/3/">Rational points on del Pezzo surfaces of degree 4</a>\nby Vladim
 ir Mitankin (Leibniz University Hannover) as part of Rational Varieties Se
 minar (Séminaire Variétés Rationnelles)\n\n\nAbstract\nIn this talk I s
 hall explain how often failures of local-to-global principles arise in a f
 amily of del Pezzo surfaces of degree four. This is addressed in terms of 
 the Brauer group. More precisely\, we give an explicit description of its 
 generators modulo constants and incorporate in the Brauer-Manin obstructio
 n the information obtained. This allows us to use tools from analytic numb
 er theory to get sharp upper and lower bounds for the number of surfaces i
 n the family with a prescribed Brauer group as well as bounds for the numb
 er of Hasse and weak approximation failures. This talk is based on a joint
  work with Cecília Salgado.\n
LOCATION:https://researchseminars.org/talk/RationalVarieties/3/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Anand Sawant (Tata Institute of Fundamental Research)
DTSTART:20210326T123000Z
DTEND:20210326T133000Z
DTSTAMP:20260422T225718Z
UID:RationalVarieties/4
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/RationalVari
 eties/4/">Near-rationality properties of algebraic varieties via A^1-conne
 ctedness</a>\nby Anand Sawant (Tata Institute of Fundamental Research) as 
 part of Rational Varieties Seminar (Séminaire Variétés Rationnelles)\n\
 n\nAbstract\nI will outline an argument proving that the standard norm\nva
 riety associated with a symbol in mod-l Milnor K-theory is R-trivial\nover
  an algebraically closed field of characteristic 0.  Rational\nconnecteded
 ness of such standard norm varieties was previously known. \nThis result i
 s achieved by relating R-triviality and retract rationality\nproperties of
  varieties with A^1-connectedness in the sense of\nMorel-Voevodsky and fin
 ding purely geometric criteria to determine\nA^1-connectedness.  The talk 
 is based on joint work with Chetan Balwe and\nAmit Hogadi.\n\nUnusual time
 !\n
LOCATION:https://researchseminars.org/talk/RationalVarieties/4/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Vivek Sadhu (Indian Institute of Science Education and Research Bh
 opal)
DTSTART:20210507T113000Z
DTEND:20210507T123000Z
DTSTAMP:20260422T225718Z
UID:RationalVarieties/5
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/RationalVari
 eties/5/">Brauer groups of valuation rings</a>\nby Vivek Sadhu (Indian Ins
 titute of Science Education and Research Bhopal) as part of Rational Varie
 ties Seminar (Séminaire Variétés Rationnelles)\n\n\nAbstract\nA classic
 al result of Auslander and Goldman says that for a regular ring R\, the Br
 auer group of R injects into the Brauer group of the function field. In th
 is talk\, I will discuss a proof of the above stated result in the case of
  arbitrary valuation rings.\n
LOCATION:https://researchseminars.org/talk/RationalVarieties/5/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Davide Lombardo (Università di Pisa)
DTSTART:20210528T140000Z
DTEND:20210528T150000Z
DTSTAMP:20260422T225718Z
UID:RationalVarieties/6
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/RationalVari
 eties/6/">Sur la distribution des points rationnels sur les revêtements d
 es variétés abéliennes</a>\nby Davide Lombardo (Università di Pisa) as
  part of Rational Varieties Seminar (Séminaire Variétés Rationnelles)\n
 \n\nAbstract\nSoit $A$ une variété abélienne définie sur un corps de n
 ombres $K$\, avec $A(K)$ Zariski-dense dans $A$. Le but de cet exposé est
  de montrer que pour tout revêtement irréductible et ramifié $\\pi : X 
 \\to A$ l'ensemble $A(K) \\setminus \\pi(X(K))$ est encore Zariski-dense d
 ans $A$ (et même qu'il contient une classe latérale de $A(K)$ sous un so
 us-groupe d'indice fini). Ce résultat est motivé par la conjecture de La
 ng sur les points rationnels des variétés de type général et confirme 
 une conjecture de Corvaja et Zannier sur la ``propriété d'Hilbert faible
 " dans le cas des variétés abéliennes.\n\nIl s'agit d'un travail en com
 mun avec P. Corvaja\, J. Demeio\, A. Javanpeykar et U. Zannier.\n
LOCATION:https://researchseminars.org/talk/RationalVarieties/6/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Martir Orr (University of Manchester)
DTSTART:20210625T113000Z
DTEND:20210625T123000Z
DTSTAMP:20260422T225718Z
UID:RationalVarieties/7
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/RationalVari
 eties/7/">The invariant Brauer group of abelian varieties</a>\nby Martir O
 rr (University of Manchester) as part of Rational Varieties Seminar (Sémi
 naire Variétés Rationnelles)\n\n\nAbstract\nCao defined the invariant Br
 auer group Br_G(X) where G is a\nconnected algebraic group and X is a smoo
 th variety on which G acts.\nThis group is useful for understanding the Br
 auer-Manin obstruction and\nstrong approximation.  If G is a linear algebr
 aic group over a field of\ncharacteristic 0\, then Br_G(G) is equal to the
  algebraic Brauer group\nBr_1(G).  However\, for an abelian variety A\, th
 e group Br_A(A) is much\nmore mysterious.\n\nIn this talk\, I will discuss
  examples of calculating Br_A(A) for an\nabelian variety\, over the comple
 x numbers and over the real numbers.\nThese two base fields are already su
 fficient for complicated behaviour\nto occur: I will present examples show
 ing that neither Br_A(A) nor\nBr_1(A) needs to be contained in the other. 
  This is joint work with A.\nSkorobogatov\, D. Valloni and Y. Zarhin.\n
LOCATION:https://researchseminars.org/talk/RationalVarieties/7/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Florian Pop (University of Pennsylvania)
DTSTART:20211029T123000Z
DTEND:20211029T160000Z
DTSTAMP:20260422T225718Z
UID:RationalVarieties/8
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/RationalVari
 eties/8/">Complements of line/hyperplane arrangements and absolute Galois 
 groups</a>\nby Florian Pop (University of Pennsylvania) as part of Rationa
 l Varieties Seminar (Séminaire Variétés Rationnelles)\n\n\nAbstract\nOn
 e of the main themes of Grothendieck’s "Esquisse d'un Programme" was to 
 give a combinatorial/topological description of absolute Galois groups. In
  this talk I plan to:\nFirst briefly recall two developments concerning th
 e above theme from the Esquisse\, namely the Grothendieck-Teichmueller gro
 up (GT) and the Ihara question/Oda-Matsumoto conjecture (I/OM)\, and expla
 in how they fit into the bigger picture about the above theme.\nSecond\, I
  plan to explain a very recent result (collaboration with Adam Topaz) conc
 erning a line/hyperplane variant of GT which: (i) is closer in nature to G
 T than I/OM is\; (ii) it gives a topological description of absolute Galoi
 s\, e.g. of that of Q.\n
LOCATION:https://researchseminars.org/talk/RationalVarieties/8/
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