Geometria_Pisa November 2024

geometria_pisa@lists.dm.unipi.it

5 participants
11 discussions

Seminario Baby Geometri 03/12
by Giovanni Framba 28 Nov '24

28 Nov '24

Carə tuttə, Vi invitiamo al seminario dei Baby Geometri della prossima settimana: Martedì 03 Dicembre 2024, alle ore 11:30 Presso l’Aula Mancini del Palazzo della Carovana Gaëtan Simian (Université de Genève) terrà un seminario dal titolo: The Arf invariant of colored links di cui riportiamo l'abstract: The Arf invariant is a modulo 2 integer associated to a non-singular quadratic form over the field F2. In 1965, Robertello applied this theory to Seifert forms, leading to an invariant of a certain class of oriented links. Colored links are a natural generalisation of oriented links, where the components are grouped into sublinks. Several invariants of oriented links, such as the Alexander module and the Levine-Tristram signature, admit natural multivariable extensions to colored links via so-called "generalised Seifert surfaces". In this talk, I will define these notions and briefly explain how to use generalised Seifert surfaces to extend the Arf-Robertello invariant to colored links. Unfortunately, these extensions turn out to be determined by the linking numbers. Vi ricordiamo che potrete trovare informazioni sui prossimi seminari sul nostro sito https://sites.google.com/view/babygeometri. Tutte le persone interessate sono invitate a partecipare. A presto, Elena Bogliolo Pietro Capovilla Alessio Di Prisa Giovanni Framba Ervin Hadžiosmanović

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First Announcement - Sub-Riemannian Geometry and Beyond, IV
by Enrico Le Donne 27 Nov '24

27 Nov '24

First Announcement Sub-Riemannian Geometry and Beyond, IV Fribourg (Switzerland), 23-28 of June 2025 https://sites.google.com/view/srgb/home/4 The 2025 meeting will focus on scientific applications of sub-Riemannian geometry. Examples of topics are Machine Learning, Modelling, Numerics, Finance, Diffusion processes, Mechanics, Image processing, Neuroscience, and Optimal Transport. ________Speakers for mini-courses Frédéric Jean -- a course on Modelling and Trajectory planning via sub-Riemannian Geometry. Jean-Marie Mirebeau -- a course on Numerical solution of sub-Riemannian Eikonal equations, and some applications. Andrea Pascucci -- a course on the role of sub-Riemannian geometry in Finance. Ludovic Rifford -- a course on the basics of sub-Riemannian geometry, and optimal transport. Alessandro Scagliotti -- a course on Machine Learning through the lens of sub-Riemannian Geometry. ________Speakers for research talks Remco Duits Peter Friz Paul Gassiat Xue-Mei Li Elisa Negrini Dario Prandi Alessandro Sarti Yannick Sire Anton Thalmaier Check more info at https://sites.google.com/view/srgb/home/4

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Seminario di Geometria del 26 Novembre - Alessio Di Prisa
by Carlo Collari 22 Nov '24

22 Nov '24

Buongiorno, Ricordo a tutti gli interessati che il prossimo seminario di geometria sarà tenuto da Alessio Di Prisa (SNS) e si terrà Martedì 26 Novembre alle ore 14:30 presso l’Aula Riunioni. Allego titolo e abstract: Titolo: On rational sliceness of negative amphichiral links. We say that a link L in S3 is negative amphichiral if there exists an orientation-reversing diffeomorphism of S3 that sends every component of L to itself with the opposite orientation. If such a map can be chosen to be an involution, then the link is said to be strongly negative amphichiral. Kawauchi proved that every strongly negative amphichiral link is rationally slice, i.e. it bounds a disjoint collection of disks in a rational homology 4-ball. In this talk, we prove that every negative amphichiral link is rationally slice, extending the aforementioned work of Kawauchi. Our proof relies on a careful analysis of the JSJ decomposition of the link complement of negative amphichiral links. This is joint work in progress with Jaewon Lee (KAIST, Daejeon) and Oğuz Şavk (CNRS, Nantes). A presto, Carlo e Filippo

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I: 3 years postdoc position at the FCG
by Paolo Lisca 22 Nov '24

22 Nov '24

Inoltro annuncio di posizione postdoc. Paolo Lisca ________________________________ Da: Alberto Abbondandolo <alberto.abbondandolo(a)rub.de> Inviato: giovedì 21 novembre 2024 18:33 Oggetto: 3 years postdoc position at the FCG Dear colleagues, The Floer Centre of Geometry in Bochum invites applications for a 3 years postdoctoral fellowship in mathematics (application’s deadline: December 15, 2024). See https://math.ruhr-uni-bochum.de/fakultaet/floer-zentrum/ for more information. We would be grateful if you could share this information with potential applicants. Best regards Alberto Abbondandolo -------------------------------------------------- Prof. Alberto Abbondandolo Ruhr-Universität Bochum Fakultät für Mathematik Gebäude IB - Raum 3/65 D-44780 Bochum Germany

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I: [rtop] BTW: Program and registration
by Paolo Lisca 21 Nov '24

21 Nov '24

Inoltro annuncio di scuola invernale. Paolo Lisca -------- Forwarded Message -------- Subject: [rtop] BTW: Program and registration Date: Wed, 20 Nov 2024 17:55:47 +0100 From: wagner(a)imj-prg.fr<mailto:wagner@imj-prg.fr> Dear fellow topologists, As previsously annouced, the 5th instance of Topology Between The Waves (aka BTW5) will occur from the 9th to the 14th of March 2025. Like last year we'll be in the Station Biologique of Besse, birth place of Nicolas Bourbaki (not too far from Clermont-Ferrand). This year's topic is a theorem by Giroux called the "Giroux correspondence". It relates open-book decompostions of 3-manifolds (topological structures) and contact structures (geometrical structures). We'll follow the proof strategy of Licata--Vertesi (on the tight case). This winter school is aimed at PhD students and young postdocs (as well as our favorite senior researchers!). The idea is to try to go through this proof together, after have learned about the necessary background. Participants are therefore encourage to give a talk (or to help preparing one). At the moment there are 15.5 talks planned see the program available here: https://lrobert.perso.math.cnrs.fr/BTW5/BTW5Program.pdf This program might changed marginally (especially if you have comment complaints or suggestions). We can have up to 35 people in Besse. Housing cost and food is covered by the conference (and we have a plan to be better on the food side, than last year). A bus shuttle from Clermont Ferrand to Besse on Sunday evening and from Besse to Clermont-Ferrand on friday afternoon will be arranged. Besides this, we do not plan to cover transport, but let us know if you have difficulties. If you want to participate, please answer to this email (with all the organizers in CC) and tell us which talk(s) suit(s) you in preference order. As usual, the final repartition will be decided as soon as possible on a first arrived first served basis with priority given to young PhD students. There is a webpage: https://lrobert.perso.math.cnrs.fr/BTW5/btw5.html Which will soon be updated. Logistical details will be provided to the participants in due time, but bare in mind that due to its relative remoteness, it is difficult to participate to only part of the week. Please circulate this announcement among your colleagues and using your usual math mailing list. Would you have any question, do not hesitate to ask the organizers. Best, Marco De Renzi Quentin Faes Jules Martel Delphine Moussard Louis-Hadrien Robert

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Seminario Baby Geometri 26/11
by Giovanni Framba 21 Nov '24

21 Nov '24

Carə tuttə, Vi invitiamo al seminario dei Baby Geometri della prossima settimana: Martedì 26 Novembre 2024, alle ore 11:30 Presso l’Aula Bianchi Lettere del Palazzo della Carovana Sofia Amontoia (Université de Genève) terrà un seminario dal titolo: Cohomologically flavoured invariants for representations di cui riporto l'abstract: Consider the set of representations of Hom(π1(M),G) for M some manifold and G an interesting Lie group. How can their nature be understood? An approach for a classification of these was kickstarted by Goldman in the 80s leading to the emergence of Higher Teichmueller theory, nowadays an actively growing field. In the talk we shall outline the essence of this approach where the so-called Toledo invariant takes a central role. Then, realizing that the Toledo invariant is actually a cohomological invariant, is the point of view that allows to generalize aspects of Goldman's classification. If time permits, we shall briefly discuss how bounded cohomology comes into play and proves to be a powerful tool. Vi ricordiamo che potrete trovare informazioni sui prossimi seminari sul nostro sito https://sites.google.com/view/babygeometri. Tutte le persone interessate sono invitate a partecipare. A presto, Elena, Pietro, Alessio, Giovanni, Ervin

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I: Topological workshop at Matemale 2025, first announcement
by Paolo Lisca 18 Nov '24

18 Nov '24

Inoltro annuncio di scuola per la prossima primavera. Paolo Lisca -------- Forwarded Message -------- Subject: Topological workshop at Matemale 2025, first announcement Date: Sat, 16 Nov 2024 22:10:36 +0100 From: thomas fiedler <thomas.fiedler(a)math.univ-toulouse.fr><mailto:thomas.fiedler@math.univ-toulouse.fr> Dear friends and colleagues, the next topological spring-summer school in Matemale (formerly Llagonne) will take place from 19/05/2025 to 23/05/2025 about Khovanov homology and exotic phenomena and is organized by Jean-François Barraud, Vincent Florens, Hoel Queffelec, Delphine Moussard and myself. You are very welcome to participate. Khovanov homology is an invariant of knots and links introduced by Khovanov in the 90s and widely studied since then. In particular, a variant of this homology due to Lee allowed Rasmussen to define a numerical invariant called the s-invariant. It appears, thanks to the work of several authors in the last years, that this s-invariant helps to detect exotic phenomena. Please forward the information to everybody who could be interested in it, especially to your students and your colleagues outside of low dimensional topology. Thanks to Delphine and Hoel we have a beautiful program which you can find on the web page https://sites.google.com/view/matemale-maths-school There will be 16 talks. Please feel free to choose a talk if you like to give one. We will be accomodated as usually in the Centre de vacances "La Capcinoise", more precisely in their gites ruraux. They have a web page https://www.lacapcinoise.fr/ . This is just for information, you don't need to make a reservation by yourself. As usual we will completely cover your stay. Please send us a mail if you are interested to participate, if you would like to give a talk and which one, and whether or not you need financial support. We hope to see you all in May! Best regards in the name of the organizers, Thomas

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Seminario Baby Geometri 19/11
by Giovanni Framba 14 Nov '24

14 Nov '24

Carə tuttə, Vi invitiamo al seminario dei Baby Geometri della prossima settimana: Martedì 19 Novembre 2024, alle ore 11:30 Presso l’Aula Seminari del Dipartimento di Matematica Julian Wyckowski (Università di Cambridge) terrà un seminario dal titolo: Three notions of accessibility for profinite groups acting on profinite trees di cui riporto l'abstract: The theory of groups acting on trees—attributed to Bass and Serre—provides a rich framework for the understanding of structural and homological properties of discrete groups. In this talk, I will introduce the profinite analogue of this theory, developed by Melnikov, Zalesskii and Ribes. I will outline some of the difficulties encountered when passing from the discrete to the profinite world, as well as some solutions. I will also introduce three notions of accessibility in the context of profinite/pro-p groups acting on profinite/pro-p trees and discuss a result of mine as well as two open questions regarding accessibility. Time permitting, I will outline some applications to other topics in profinite rigidity. Vi ricordiamo che potrete trovare informazioni sui prossimi seminari sul nostro sito https://sites.google.com/view/babygeometri. Tutte le persone interessate sono invitate a partecipare. A presto, Elena, Pietro, Alessio, Giovanni, Ervin

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Pranzo con lo speaker
by Carlo Collari 12 Nov '24

12 Nov '24

Buongiorno, Per tutti gli interessati ad andare a pranzo con lo speaker del seminario di Geometria di oggi, l'appuntamento è alle 13 in atrio. A presto, Carlo

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Seminario di Geometria del 29 Ottobre - Nikolay Abrosimov
by Carlo Collari 10 Nov '24

10 Nov '24

Buongiorno, Ricordo a tutti gli interessati che il prossimo seminario di geometria sarà tenuto da Nikolay Abrosimov e si terrà Martedì 12 Novembre alle ore 14:30 presso l’Aula Magna. Allego titolo e abstract: Titolo: Euclidean volume of a cone manifold over any hyperbolic knot is an algebraic number Abstract: The talk is based on our joint work [1] with Alexander Kolpakov (Université de Neuchâtel, Switzerland) and Alexander Mednykh (Sobolev Institute of Mathematics, Novosibirsk). A hyperbolic structure on a three-dimensional cone manifold with a knot as a singular set can usually be deformed into a limit Euclidean structure. In our paper [1] we show that the corresponding normalized Euclidean volume of the manifold is always an algebraic number i.e. a root of some polynomial with integer coefficients. This result is a generalization (for cone manifolds) of the well-known Sabitov theorem on the volumes of Euclidean polyhedra which gave an answer to the bellows problem. The fact we established stands out against the background of hyperbolic volumes the number-theoretic nature of which is usually quite complex. In addition to this theorem we propose an algorithm that allows one to explicitly calculate the minimal polynomial for a normalized Euclidean volume. References: [1] N. Abrosimov A. Kolpakov A. Mednykh Euclidean volumes of hyperbolic knots // Proc. Amer. Math. Soc. 152 (2024) 869-881. DOI: 10.1090/proc/16353 A presto, Filippo

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Geometria_Pisa November 2024