- Geometria_Pisa - Mailing list — Dipartimento di Matematica, UniPI

Seminario di Geometria Giovedì 20 Febbraio - Nicoletta Tardini
by Carlo Collari 17 Feb '25

17 Feb '25

Buongiorno, Vi ricordo che il prossimo seminario di Geometria e Topologia sarà tenuto da Nicoletta Tardini e si terrà Giovedì 20 Febbraio alle ore 14:30 presso l'aula Riunioni. Per gli interessati ad andare a pranzo con la speaker, l'appuntamento è in atrio alle 13:00. Allego titolo e abstract Titolo: Special Hermitian metrics on complex manifolds Abstract: Kähler geometry lies at the intersection of complex geometry, Riemannian geometry and symplectic geometry. From the complex geometric point of view it is therefore natural to consider special non-Kähler Hermitian metrics on complex manifolds. Among them, pluriclosed metrics deserve particular attention. These metrics always exist on compact complex surfaces but the situation in higher dimension is very different. We will discuss several properties concerning these metrics also in relation with the Bismut connection having Kähler-like curvature. This is joint work with G. Barbaro and F. Pediconi A presto, Carlo e Filippo

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Workshop "Manifolds and Groups in Bologna, III", announcement
by Filippo Sarti 06 Feb '25

06 Feb '25

Dear all, we are pleased to announce the workshop Manifolds and Groups in Bologna, III ----------------------------------------- Date: Monday, Apr 14, 2025 -- Wednesday , Apr 16, 2025 Place: University of Bologna The aim of this workshop is to bring together young researchers working in low-dimensional topology and geometric group theory in a broad sense. The event consists of main lectures and shorter talks in order to give the opportunity to young researchers to present their own research. Main speakers: Naomi Andrew (Oxford), Macarena Arenas (Cambridge), Carlo Collari (Pisa), James Farre (MPI MIS Leipzig), Mitul Islam (MPI MIS Leipzig), Stavroula Makri (Toulouse), Lorenzo Ruffoni (Binghamton), Matthias Uschold (Regensburg). Junior speakers: Sofia Amontova (Geneva), Valentina Bais (SISSA), Filippo Bianchi (Pisa), Elena Bogliolo (Pisa), Alberto Casali (Pisa), Bruno Dular (Luxembourg), Franziska Hofmann (Regensburg). https://math.unibo.it/en/events/manifolds-and-groups-in-bologna-2025 Looking forward to seeing you in Bologna, Giuseppe Bargagnati, Marco Moraschini, Stefano Riolo (University di Bologna) and Filippo Sarti (University of Pisa)

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seminario di lettura
by Paolo Lisca 05 Feb '25

05 Feb '25

Ciao a tutti, vorrei organizzare un seminario di lettura su questo articolo<https://arxiv.org/abs/2402.10452>, che fornisce la prima dimostrazione dell'esistenza di 4-varietà esotiche compatte orientabili senza l'uso di analisi. Ci sarà un incontro preliminare martedì 11 febbraio alle 14:30 nella saletta seminari. Chi non può (ma vorrebbe) venire martedì mi avverta! A presto, Paolo

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Seminario di Geometria Giovedì 6 Febbraio - Michelle Bucher
by Carlo Collari 03 Feb '25

03 Feb '25

Buongiorno, Vi ricordo che il prossimo seminario di Geometria e Topologia sarà tenuto da Michelle Bucher e si terrà Giovedì 6 Febbraio alle ore 14:30 presso l'aula Riunioni. Per gli interessati ad andare a pranzo con la speaker, l'appuntamento è in atrio alle 13:00. Allego titolo e abstract Titolo: Continuous cocycles on the Furstenberg boundary and applications to bounded cohomology Abstract: Group cohomology comes in many variations. The standard Eilenberg-MacLane group cohomology is the cohomology of the cocomplex {f:Gq+1→R∣f is G−invariant}{f:Gq+1→R∣f is G−invariant} endowed with its natural homogeneous coboundary operator. Now whenever a property P of such cochains is preserved under the coboundary one can obtain the corresponding P-group cohomology. P could be: continuous, measurable, L0L0, bounded, alternating, etc. Sometimes these various cohomology groups are known to differ (eg P=empty and P=continuous for most topological groups), in other cases they are isomorphic (eg P=empty and P=alternating (easy), P=continuous and P=L0L0 (a highly nontrivial result by Austin and Moore valid for locally compact second countable groups)). In 2006, Monod conjectured that for semisimple connected, finite center, Lie groups of noncompact type, the natural forgetful functor induces an isomorphism between continuous bounded cohomology and continuous cohomology (which is typically very wrong for discrete groups). I will focus here on the injectivity and show its validity in several new cases including isometry groups of hyperbolic nn-spaces in degree 4, known previously only for n=2n=2 by a tour de force due to Hartnick and Ott. Monod recently proved that all such continuous (bounded) cohomology classes can be represented by measurable (bounded) cocycles on the Furstenberg boundary. Our main result is that these cocycles can be chosen to be continuous on a subset of full measure. In the real hyperbolic case, this subset of full measure is the set of distinct tuples of points, easily leading to the injectivity in degree 4. This is joint work with Alessio Savini. A presto, Carlo e Filippo

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Seminario di Geometria 30 Gennaio - Elia Fioravanti
by Carlo Collari 27 Jan '25

27 Jan '25

Buongiorno, Vi ricordo che il prossimo seminario di Geometria e Topologia sarà tenuto da Elia Fioravanti e si terrà Giovedì 30 Gennaio alle ore 14:30 presso l'aula Riunioni. Per gli interessati ad andare a pranzo con lo speaker, l'appuntamento è in atrio alle 13:00. Allego titolo e abstract Titolo: Growth of automorphisms of special groups Abstract: Given a (nice) group G, we are interested in how fast the length of a group element can grow when we apply powers of a given outer automorphism of G. If the group G is free or the fundamental group of a closed surface, classical train-track techniques give a complete and precise picture. This can be extended to automorphisms of all negatively curved (a.k.a. Gromov hyperbolic) groups G, using Rips-Sela theory and the canonical JSJ decomposition. Very little seems to be known beyond this setting. We study this problem for a broad class of non-positively curved groups: "virtually special" groups in the Haglund-Wise sense. In this setting, we prove that: (1) the stretch factor of any automorphism is an algebraic integer; (2) if the automorphism is untwisted, then it admits only finitely many growth rates, each of these is polynomial-times-exponential, and there is a Nielsen-Thurston decomposition. A presto, Carlo e Filippo

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Seminario di Geometria 23 Gennaio - Macarena Arenas
by Carlo Collari 21 Jan '25

21 Jan '25

Buongiorno, Vi ricordo che il prossimo seminario di Geometria e Topologia sarà tenuto da Macarena Arenas e si terrà Giovedì 23 Gennaio alle ore 14:30 presso l'aula Riunioni. Per gli interessati ad andare a pranzo con la speaker, l'appuntamento è in atrio alle 13:00. Allego titolo e abstract Titolo: Taut smoothings and shortest geodesics Abstract: In this talk we will discuss the connection between combinatorial properties of minimally self-intersecting curves on a surface S and the geometric behaviour of geodesics on S when S is endowed with a Riemannian metric. In particular, we will explain the interplay between a smoothing, which is a type of surgery on a curve that resolves a self-intersection, and k-systoles, which are shortest geodesics having at least k self-intersections, and we will present some results that partially elucidate this interplay. A presto, Carlo e Filippo

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Seminario di Geometria 16 Gennaio - Francesco Bonsante
by Carlo Collari 13 Jan '25

13 Jan '25

Buongiorno, Ricominciano i seminari di Geometria e Topologia! Il primo seminario di quest'anno sarà tenuto da Francesco Bonsante e si terrà Giovedì 16 Gennaio alle ore 14:30 presso l'aula Riunioni. Per gli interessati ad andare a pranzo con lo speaker, l'appuntamento è in atrio alle 13:00. Allego titolo e abstract: Titolo: Rigidità di circle packings su superfici proiettive Abstact: I circle packing su superfici iperboliche (o più in generale su superfici Riemanniane a curvatura costante) sono collezioni di dischi mutualmente tangenti, tali che il complementare dell’unione di tali dischi sia un’unione disgiunta di interstizi triangolari. Essi sono stati inizialmente studiati da Thurston che ne ha dimostrato un importante risultato di rigidità: fissata la combinatoria della collezione dei dischi esiste un un’unica superficie iperbolica su cui il circle packing può essere realizzato. Più recentemente Kojima Mitzushima e S.Tan hanno osservato che la nozione di disco su CP1 e invariante per trasformazioni proiettive e dunque ha senso parlare di dischi e di circle packing su superfici munite di strutture proiettive complesse. Essi hanno osservato che lo spazio delle strutture proiettive munite di circle packing con una combinatoria fissata è descritto da una varietà algebrica reale di dimensione 6g−6, dove g è il genere della superficie e hanno lasciato aperte tre domande: (1) stabilire se tale varietà algebrica sia liscia, (2) stabilire se l’inclusione naturale di tale spazio nello spazio delle strutture proiettive sia un’immersione, (3) stabilire se la mappa che associa a ogni elemento di questa varietà la struttura complessa soggiacente sia un locale diffeo. Nel seminario parlerò di questi problemi e di alcuni risultati parziali recentemente ottenuti in collaborazione con Mike Wolf. A presto, Carlo e Filippo

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Scuola di topologia
by Bruno Martelli 10 Jan '25

10 Jan '25

Segnalo questa scuola che mi sembra molto adatta per i topologi pisani Bruno https://www.icmat.es/schools/2025/MSBG/index.php

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Fwd: Fw: Postdoc in Bilbao
by Bruno Martelli 10 Jan '25

10 Jan '25

---------- Forwarded message --------- Da: Llosa, Claudio (IAG) <claudio.llosa(a)kit.edu> Date: Mar 7 Gen 2025, 18:50 Subject: Fw: Postdoc in Bilbao To: Bruno Martelli <bruno.martelli(a)unipi.it> Karlsruhe Institute of Technology (KIT) Institute for Algebra and Geometry JProf. Dr. Claudio Llosa Isenrich Juniorprofessor for Geometry KIT Faculty of Mathematics Englerstraße 2 <https://www.google.com/maps/search/Englerstra%C3%9Fe+2+%0D%0A76131+Karlsruh…> 76131 Karlsruhe, Germany <https://www.google.com/maps/search/Englerstra%C3%9Fe+2+%0D%0A76131+Karlsruh…> Phone: +49 721 608-43914 Email: claudio.llosa(a)kit.edu Website: https://www.math.kit.edu/iag2/~llosa/en Registered office: Kaiserstraße 12, 76131 Karlsruhe, Germany <https://www.google.com/maps/search/Kaiserstra%C3%9Fe+12,+76131+Karlsruhe,+G…> KIT – The Research University in the Helmholtz Association ------------------------------ *From:* geom-group-theory-request(a)lists.illinois.edu < geom-group-theory-request(a)lists.illinois.edu> on behalf of MONTSERRAT CASALS RUIZ <montserrat.casals(a)ehu.eus> *Sent:* Tuesday, January 7, 2025 9:20:44 AM *To:* geom-group-theory(a)lists.illinois.edu *Subject:* [geom-group-theory] Postdoc in Bilbao Dear colleagues, We are pleased to advertise a *two-year postdoctoral *position in geometric group theory, based at the University of the Basque Country (UPV-EHU) in *Bilbao* and mentored by Montserrat Casals-Ruiz. The position comes with no compulsory teaching load, and there will be a possibility of obtaining additional funding to extend the contract through December 2027. The starting date is negotiable, contingent on the candidate fulfilling the requirements set by the Spanish administration, although it should be no later than October 2025. The salary will be according to the Convenio colectivo de personal laboral docente e investigador de la UPV/EHU (approximately 38,000 euros, before tax). This position is part of the project “Mapping class groups from above and from below”, funded by the Agencia Estatal de Investigación (AEI) and the Deutsche Forschungsgemeinschaft (DFG), as a collaboration of Javier Aramayona (ICMAT), Montserrat Casals-Ruiz (Bilbao), Elia Fioravanti (KIT), Claudio Llosa-Isenrich (KIT), and Katrin Tent (Münster). There will be numerous opportunities for interactions with researchers based at the other three institutions. Candidates with expertise related to the project themes are particularly encouraged to apply. These include, but are not limited to: right-angled Artin groups, actions on R-trees and cube complexes; mapping class groups; Burnside groups and small cancellation theory; and Kähler groups. Interested candidates should submit a CV, a research statement (maximum 2 pages), and a cover letter to mafabproject(a)gmail.com using the subject "Postdoc MAFAB Bilbao", before *February 7, 2025*. Additionally, applicants may arrange for up to two referees to send recommendation letters directly to the same email address. Please note that we will not contact referees to request letters on behalf of the applicants. For further information, please feel free to contact us informally per email. Montse Casals-Ruiz

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Fwd: Fw: 2-year postdoc in Karlsruhe or Muenster
by Bruno Martelli 10 Jan '25

10 Jan '25

---------- Forwarded message --------- Da: Llosa, Claudio (IAG) <claudio.llosa(a)kit.edu> Date: Mar 7 Gen 2025, 18:48 Subject: Fw: 2-year postdoc in Karlsruhe or Muenster To: Bruno Martelli <bruno.martelli(a)unipi.it> ------------------------------ *From:* geom-group-theory-request(a)lists.illinois.edu < geom-group-theory-request(a)lists.illinois.edu> on behalf of Fioravanti, Elia (IAG) <elia.fioravanti(a)kit.edu> *Sent:* Tuesday, January 7, 2025 10:19:57 AM *To:* geom-group-theory(a)lists.illinois.edu *Subject:* [geom-group-theory] 2-year postdoc in Karlsruhe or Muenster Dear Colleagues, We would like to advertise a 2-year postdoc position in Geometric Group Theory, to be based either at the Karlsruhe Institute of Technology or at the University of Münster, under the mentorship of Elia Fioravanti, Claudio Llosa Isenrich or Katrin Tent. The position comes with no compulsory teaching load and there may be the possibility of an extension to a 3rd year. It is paid according to the German E13 TV-L pay grade. The starting date is flexible, though it should be in October 2025 at the latest. The position is part of the project "Mapping class groups from above and below", jointly funded by the German and Spanish Research Foundations as a collaboration of Fioravanti, Llosa Isenrich and Tent with Javier Aramayona (Madrid) and Montserrat Casals-Ruiz (Bilbao). There will be numerous opportunities for interactions with researchers based at the other three institutions. Project topics include, but are not limited to: Burnside groups and small cancellation theory; Kähler groups; actions on R-trees and cube complexes; mapping class groups and Out(F_n). Applications should be submitted via email at the address mafab-project(a)lists.kit.edu and should consist of the following documents (as a single pdf file): - a CV, including list of publications; - a research statement outlining past and future research (max 2 pages); - a cover letter which also indicates a preferred choice of host institution ; - 2 letters of recommendation, to be submitted at the same address by the referees. All documents must be received by the deadline of *7 February 2025*. Please note that we will not contact referees to request letters on behalf of the applicants. For further information, please feel welcome to contact us informally per email. Best wishes, Elia Fioravanti (KIT), Claudio Llosa Isenrich (KIT), Katrin Tent (Münster)

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