BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//TYPO3/NONSGML Calendarize//EN
BEGIN:VEVENT
UID:calendarize-spectral-analysis-of-a-closed-perturbed-waveguide-filled-w
 ith-a-hyperbolic-medium
DTSTAMP:20260420T091257Z
DTSTART:20260507T123000Z
DTEND:20260507T133000Z
SUMMARY:Spectral analysis of a closed perturbed waveguide filled with a hy
 perbolic medium
DESCRIPTION:Lecture announcement\nIn the context of the advanced seminar A
 nalysis/NumericsMr Dylan Machado(ENSTA Paris)\nabout\nSpectral analysis of
  a closed perturbed waveguide filled with a hyperbolic medium\nAbstract: W
 e investigate the spectrum of the first-order operator that governs the pr
 opagationof electromagnetic waves in the case of a closed locally perturbe
 d waveguide filled with ahyperbolic medium. The perturbation is localized 
 on the boundary and we imposehomogeneous Dirichlet boundary conditions.Fro
 m a physics perspective\, this type of medium falls within the class of hy
 perbolicelectromagnetic metamaterials. They are artificial media which exh
 ibit a lot of interesting andpromising physics phenomena such as negative 
 refraction\, rainbow-trapping and enhancedspontaneous emission.In practice
 \, the simplest mathematical model stems from electromagnetic wave propaga
 tion ina strongly magnetized cold plasma. It is described by 2D Maxwell eq
 uations which\, in theirtime-harmonic form\, may be reduced to the Klein-G
 ordon equation for a certain range offrequencies\, namely the hyperbolic f
 requencies. Hence\, the nature of the problem is purelyhyperbolic.Firstly\
 , we prove a limiting absorption principle (LAP) for the hyperbolic freque
 ncies satisfyinga geometric condition on the perturbation. The latter is r
 elated to the interplay between thevelocities of the boundary and of the p
 ropagating waves\, which\, in our case\, depends on thefrequency. This ran
 ge of frequency is called the subsonic regime. The key idea of our work is
 the use of the well-posedness and energy estimates of the Klein-Gordon equ
 ation in boundedtime-dependent domains.The second part of the talk will be
  devoted to the 'supersonic' regime: the frequencies for whichthe boundary
  moves faster than the waves. In particular\, the Klein-Gordon equation in
  arbitrarytime-dependent domains is no longer well-posed for homogeneous D
 irichlet boundaryconditions. Nevertheless\, we are still able to prove a L
 AP by using the weak observabilityresults of waves and exchanging the role
  of the time and space variables. \nThe lecture will take place onThursday
 \, 07.05.2026at 14.30 - 15.30 in room W01 1-117\nInterested parties are co
 rdially invited.
X-ALT-DESC;FMTTYPE=text/html:<h2 class="text-center">Lecture announcement<
 /h2>\n<h3 class="text-center"><br><strong>In the context of the advanced s
 eminar Analysis/Numerics<br></strong><i><strong>Mr Dylan Machado</strong><
 /i><strong><br>(ENSTA Paris)</strong></h3>\n<p class="text-center"><br />a
 bout</p>\n<h2 class="text-center"><br><strong>Spectral analysis of a close
 d perturbed waveguide filled with a hyperbolic medium</strong></h2>\n<p cl
 ass="text-center"><br />Abstract: We investigate the spectrum of the first
 -order operator that governs the propagation<br />of electromagnetic waves
  in the case of a closed locally perturbed waveguide filled with a<br />hy
 perbolic medium. The perturbation is localized on the boundary and we impo
 se<br />homogeneous Dirichlet boundary conditions.<br />From a physics per
 spective\, this type of medium falls within the class of hyperbolic<br />e
 lectromagnetic metamaterials. They are artificial media which exhibit a lo
 t of interesting and<br />promising physics phenomena such as negative ref
 raction\, rainbow-trapping and enhanced<br />spontaneous emission.<br />In
  practice\, the simplest mathematical model stems from electromagnetic wav
 e propagation in<br />a strongly magnetized cold plasma. It is described b
 y 2D Maxwell equations which\, in their<br />time-harmonic form\, may be r
 educed to the Klein-Gordon equation for a certain range of<br />frequencie
 s\, namely the hyperbolic frequencies. Hence\, the nature of the problem i
 s purely<br />hyperbolic.<br />Firstly\, we prove a limiting absorption pr
 inciple (LAP) for the hyperbolic frequencies satisfying<br />a geometric c
 ondition on the perturbation. The latter is related to the interplay betwe
 en the<br />velocities of the boundary and of the propagating waves\, whic
 h\, in our case\, depends on the<br />frequency. This range of frequency i
 s called the subsonic regime. The key idea of our work is<br />the use of 
 the well-posedness and energy estimates of the Klein-Gordon equation in bo
 unded<br />time-dependent domains.<br />The second part of the talk will b
 e devoted to the 'supersonic' regime: the frequencies for which<br />the b
 oundary moves faster than the waves. In particular\, the Klein-Gordon equa
 tion in arbitrary<br />time-dependent domains is no longer well-posed for 
 homogeneous Dirichlet boundary<br />conditions. Nevertheless\, we are stil
 l able to prove a LAP by using the weak observability<br />results of wave
 s and exchanging the role of the time and space variables.<br /> </p>\n<h4
  class="text-center"><strong>The lecture will take place on<br>Thursday\, 
 07.05.2026<br>at 14.30 - 15.30 in room W01 1-117</strong></h4>\n<p class="
 text-center"><br />Interested parties are cordially invited.</p>
LOCATION:
END:VEVENT
BEGIN:VEVENT
UID:calendarize-lagrange-theory-on-jet-bundles-and-variational-completion
DTSTAMP:20260422T142641Z
DTSTART:20260430T123000Z
DTEND:20260430T133000Z
SUMMARY:Lagrange theory on jet bundles and variational completion
DESCRIPTION:Lecture announcement\n \nAs part of the advanced seminar Analy
 sis/Numerics\n \nMr PD Dr Manuel Hohmann\n(University of Tartu)\nabout\n \
 nLagrange theory on jet bundles and variational completion\n \nAbstract: O
 ne of the most fundamental principles used in theoretical physics is the s
 tationary action principle. It states that the classical solutions of a ph
 ysical system are the stationary solutions of an action functional\, defin
 ed on its phase space. This leads to the Euler-Lagrange equations by apply
 ing variational calculus\, in a straightforward calculation. A more diffic
 ult question is the so-called inverse problem of variational calculus: giv
 en a set of differential equations\, 1. do these equations arise from vari
 ation of an action\, 2. how to find the action? Both questions can be answ
 ered by the method of variational completion\, and calculating the so-call
 ed Vainberg-Tonti Lagrangian. However\, this classical method is dependent
  on the choice of coordinates\, and requires certain conditions on the dom
 ain of definition of the system. In my talk\, I present the proper geometr
 ic framework for the Lagrange formalism and the inverse problem in terms o
 f jet bundles\, at a beginner level. Then I show how the classical Vainber
 g-Tonti procedure can be generalised in a coordinate-independent fashion. 
 \n \nThe lecture will take place on\n \nThursday\, 30.04.2026at 14.30 - 15
 .30 in room W01 1-117\n \n \nInterested parties are cordially invited.\n 
X-ALT-DESC;FMTTYPE=text/html:<h2 class="text-center"><span><strong>Lecture
  announcement</strong></span></h2>\n<p class="text-center"> </p>\n<p class
 ="text-center">As part of the advanced seminar Analysis/Numerics</p>\n<p c
 lass="text-center"> </p>\n<h3 class="text-center"><span lang="EN-GB" dir="
 ltr"><strong>Mr PD Dr Manuel Hohmann</strong></span></h3>\n<h3 class="text
 -center"><span lang="EN-GB" dir="ltr"><strong>(University of Tartu)</stron
 g></span></h3>\n<p class="text-center"><span lang="EN-US" dir="ltr">about<
 /span></p>\n<p class="text-center"> </p>\n<h2 class="text-center"><span la
 ng="EN-GB" dir="ltr"><strong>Lagrange theory on jet bundles and variationa
 l completion</strong></span></h2>\n<p class="text-center"> </p>\n<p class=
 "text-justify"><i><span lang="EN-GB" dir="ltr"><strong>Abstract:</strong> 
 </span><span lang="EN-US" dir="ltr">One of the most fundamental principles
  used in theoretical physics is the stationary action principle. It states
  that the classical solutions of a physical system are the stationary solu
 tions of an action functional\, defined on its phase space. This leads to 
 the Euler-Lagrange equations by applying variational calculus\, in a strai
 ghtforward calculation. A more difficult question is the so-called inverse
  problem of variational calculus: given a set of differential equations\, 
 1. do these equations arise from variation of an action\, 2. how to find t
 he action? Both questions can be answered by the method of variational com
 pletion\, and calculating the so-called Vainberg-Tonti Lagrangian. However
 \, this classical method is dependent on the choice of coordinates\, and r
 equires certain conditions on the domain of definition of the system. In m
 y talk\, I present the proper geometric framework for the Lagrange formali
 sm and the inverse problem in terms of jet bundles\, at a beginner level. 
 Then I show how the classical Vainberg-Tonti procedure can be generalised 
 in a coordinate-independent fashion. </span></i></p>\n<p class="text-justi
 fy"> </p>\n<p class="text-center">The lecture will take place on</p>\n<p c
 lass="text-center"> </p>\n<p class="text-center"><strong>Thursday\, 30.04.
 2026<br />at 14.30 - 15.30 in room W01 1-117</strong></p>\n<p class="text-
 center"> </p>\n<p class="text-center"> </p>\n<p class="text-center">Intere
 sted parties are cordially invited.</p>\n<p class="text-center"> </p>
LOCATION:
END:VEVENT
BEGIN:VEVENT
UID:calendarize-stochastic-completeness-and-the-calabi-yau-conjectures
DTSTAMP:20260422T091345Z
DTSTART:20260423T131500Z
DTEND:20260423T140000Z
SUMMARY:Stochastic completeness and the Calabi-Yau conjectures
DESCRIPTION:Lecture announcement\nAs part of the advanced seminar Analysis
 /Numerics\,Dr Giuseppe Gentile will speak\nabout\nStochastic completeness 
 and the Calabi-Yau conjectures\nAbstract: In this talk I will present rece
 nt developments on the geometric properties of minimalsubmanifolds and har
 monic maps\, motivated by the classical Calabi-Yau conjectures. Theseconje
 ctures predict that minimal hypersurfaces in Euclidean space\, as well as 
 certain of theirprojections\, must be unbounded. While striking counterexa
 mples show that the conjectures failin general for immersed surfaces\, the
 y remain true under additional geometric assumptions. Iwill explain how st
 ochastic completeness\, viewed as a weak maximum principle for noncompact 
 manifolds\, together with a flexible notion of convexity (pullvexity)\, ca
 n be used torecover such unboundedness results. This is joint work with Re
 nan Assimos and BalázsBékési.\nThe lecture will take place onThursday\,
  23.04.2026at 15.15 - 16.00 in room W01 1-117\nInterested parties are cord
 ially invited.
X-ALT-DESC;FMTTYPE=text/html:<h2 class="text-center">Lecture announcement<
 /h2>\n<h3 class="text-center"><br>As part of the advanced seminar Analysis
 /Numerics\,<br><strong>Dr Giuseppe Gentile</strong> will speak</h3>\n<p cl
 ass="text-center">about</p>\n<h2 class="text-center"><strong>Stochastic co
 mpleteness and the Calabi-Yau conjectures</strong></h2>\n<p class="text-ce
 nter"><br />Abstract: In this talk I will present recent developments on t
 he geometric properties of minimal<br />submanifolds and harmonic maps\, m
 otivated by the classical Calabi-Yau conjectures. These<br />conjectures p
 redict that minimal hypersurfaces in Euclidean space\, as well as certain 
 of their<br />projections\, must be unbounded. While striking counterexamp
 les show that the conjectures fail<br />in general for immersed surfaces\,
  they remain true under additional geometric assumptions. I<br />will expl
 ain how stochastic completeness\, viewed as a weak maximum principle for n
 oncompact manifolds\, together with a flexible notion of convexity (pullve
 xity)\, can be used to<br />recover such unboundedness results. This is jo
 int work with Renan Assimos and Balázs<br />Békési.</p>\n<p class="text
 -center"><br /><strong>The lecture will take place on<br />Thursday\, 23.0
 4.2026<br />at 15.15 - 16.00 in room W01 1-117</strong></p>\n<p class="tex
 t-center"><br />Interested parties are cordially invited.</p>
LOCATION:
END:VEVENT
BEGIN:VEVENT
UID:calendarize-resolving-the-tragedy-of-modelers
DTSTAMP:20260422T091514Z
DTSTART:20260423T121500Z
DTEND:20260423T131500Z
SUMMARY:Resolving the tragedy of modelers
DESCRIPTION:Lecture announcement\n \nAs part of the advanced seminar Analy
 sis/Numerics\nDr Alexey Ryabov\n(ICBM\, University of Oldenburg)\nabout\nR
 esolving the tragedy of modelers\n \nAbstract: In this presentation\, I wi
 ll discuss a critical problem in ecological modelling\, which I\nrefer to 
 here as the "modelers' tragedy". This challenge arises because to model ec
 ological\nsystems we have to rely on incomplete functional relationships\,
  usually obtained in laboratory\nconditions. These relationships often cov
 er only a few factors\, failing to represent the nature\ncomplexity and om
 itting factors for which there is insufficient data. It's like putting tog
 ether a\npuzzle with missing pieces - a real tragedy. Even when we careful
 ly fit parameters enabling\nmodels to predict dynamics over a given period
 \, doubts remain about the accuracy of the model\nin reflecting true inter
 nal processes and its future predictive power.\nTo solve this problem\, we
  propose a new approach: "nonparametric population dynamic\nmodelling". Th
 is method abandons predefined functional relationships by extracting this\
 ninformation directly from field data. We combine dynamic modelling with a
  machine learning\ntechnique known as parameter regularisation\, aiming to
  identify the simplest models that best generalize the\ngeneralise the dat
 a.\n \nOur process begins with fitting a baseline model to a time series o
 f species abundance\,\nassuming e.g. constant birth and death rates. We th
 en determine the minimum parameter\ndeviations needed at each time point o
 f observation (e.g.\, annually) to accurately reflect\npopulation dynamics
 . By analysing how these parameter deviations relate to environmental\nfac
 tors\, we determine environmental effects on population growth and loss ra
 tes.\nWe demonstrate this method using the example of Antarctic krill\, a 
 key species in the\nSouthern Ocean's fishery and food web. Our approach de
 termines how variables such as\ntemperature\, food availability\, and ice 
 cover affect krill population losses throughout the year\nand at different
  life stages. Ultimately\, we show how these findings can be incorporated 
 into a\nstatistical dynamic model that describes the population dynamics o
 f Antarctic krill.\n1 A. Ryabov\, U. Berger\, B. Blasius\, B. Meyer\, Driv
 ing forces of Antarctic krill abundance.\nScience Advances 9\, eadh4584 (2
 023). https://www.science.org/doi/10.1126/sciadv.adh4584\n \nSchool V\n \n
 Mathematics and Natural Sciences\n \nThe lecture will take place on\nThurs
 day\, 23.04.2026 at 14.15 - 15.15 in room W01 1-117\n \nInterested parties
  are cordially invited.  
X-ALT-DESC;FMTTYPE=text/html:<p class="text-center"><span class="fontstyle
 0">Lecture announcement</span></p>\n<p class="text-center"> </p>\n<p class
 ="text-center"><span class="fontstyle1">As part of the advanced seminar An
 alysis/Numerics</span></p>\n<p class="text-center"><i><span class="fontsty
 le0"><strong>Dr Alexey Ryabov</strong></span></i></p>\n<p class="text-cent
 er"><span class="fontstyle0">(ICBM\, University of Oldenburg)</span></p>\n
 <p class="text-center"><span class="fontstyle1">about</span></p>\n<h2 clas
 s="text-center"><span class="fontstyle1"><strong>Resolving the tragedy of 
 modelers</strong></span></h2>\n<p class="text-center"> </p>\n<p class="tex
 t-center"><span class="fontstyle0"><strong>Abstract</strong>: </span><span
  class="fontstyle1">In this presentation\, I will discuss a critical probl
 em in ecological modelling\, which I</span></p>\n<p class="text-center"><s
 pan class="fontstyle1">refer to here as the "modelers' tragedy". This chal
 lenge arises because to model ecological</span></p>\n<p class="text-center
 "><span class="fontstyle1">systems we have to rely on incomplete functiona
 l relationships\, usually obtained in laboratory</span></p>\n<p class="tex
 t-center"><span class="fontstyle1">conditions. These relationships often c
 over only a few factors\, failing to represent the nature</span></p>\n<p c
 lass="text-center"><span class="fontstyle1">complexity and omitting factor
 s for which there is insufficient data. It's like putting together a</span
 ></p>\n<p class="text-center"><span class="fontstyle1">puzzle with missing
  pieces - a real tragedy. Even when we carefully fit parameters enabling</
 span></p>\n<p class="text-center"><span class="fontstyle1">models to predi
 ct dynamics over a given period\, doubts remain about the accuracy of the 
 model</span></p>\n<p class="text-center"><span class="fontstyle1">in refle
 cting true internal processes and its future predictive power.</span></p>\
 n<p class="text-center"><span class="fontstyle1">To solve this problem\, w
 e propose a new approach: "nonparametric population dynamic</span></p>\n<p
  class="text-center"><span class="fontstyle1">modelling". This method aban
 dons predefined functional relationships by extracting this</span></p>\n<p
  class="text-center"><span class="fontstyle1">information directly from fi
 eld data. We combine dynamic modelling with a machine learning</span></p>\
 n<p class="text-center"><span class="fontstyle1">technique known as parame
 ter regularisation\, aiming to identify the simplest models that best gene
 ralize the</span></p>\n<p class="text-center"><span class="fontstyle1">gen
 eralise the data.</span></p>\n<p class="text-center"> </p>\n<p class="text
 -center"><span class="fontstyle1">Our process begins with fitting a baseli
 ne model to a time series of species abundance\,</span></p>\n<p class="tex
 t-center"><span class="fontstyle1">assuming e.g. constant birth and death 
 rates. We then determine the minimum parameter</span></p>\n<p class="text-
 center"><span class="fontstyle1">deviations needed at each time point of o
 bservation (e.g.\, annually) to accurately reflect</span></p>\n<p class="t
 ext-center"><span class="fontstyle1">population dynamics. By analysing how
  these parameter deviations relate to environmental</span></p>\n<p class="
 text-center"><span class="fontstyle1">factors\, we determine environmental
  effects on population growth and loss rates.</span></p>\n<p class="text-c
 enter"><span class="fontstyle1">We demonstrate this method using the examp
 le of Antarctic krill\, a key species in the</span></p>\n<p class="text-ce
 nter"><span class="fontstyle1">Southern Ocean's fishery and food web. Our 
 approach determines how variables such as</span></p>\n<p class="text-cente
 r"><span class="fontstyle1">temperature\, food availability\, and ice cove
 r affect krill population losses throughout the year</span></p>\n<p class=
 "text-center"><span class="fontstyle1">and at different life stages. Ultim
 ately\, we show how these findings can be incorporated into a</span></p>\n
 <p class="text-center"><span class="fontstyle1">statistical dynamic model 
 that describes the population dynamics of Antarctic krill.</span></p>\n<p 
 class="text-center"><span class="fontstyle1">1 A. Ryabov\, U. Berger\, B. 
 Blasius\, B. Meyer\, Driving forces of Antarctic krill abundance.</span></
 p>\n<p class="text-center"><span class="fontstyle1">Science Advances 9\, e
 adh4584 (2023). https://www.science.org/doi/10.1126/sciadv.adh4584</span><
 /p>\n<p class="text-center"> </p>\n<p class="text-center"><span class="fon
 tstyle0">School V</span></p>\n<p class="text-center"> </p>\n<p class="text
 -center"><span class="fontstyle1">Mathematics and Natural Sciences</span><
 /p>\n<p class="text-center"> </p>\n<p class="text-center"><span class="fon
 tstyle1"><strong>The lecture will take place on</strong></span></p>\n<p cl
 ass="text-center"><span class="fontstyle0"><strong>Thursday\, 23.04.2026 a
 t 14.15 - 15.15 in room W01 1-117</strong></span></p>\n<p class="text-cent
 er"> </p>\n<p class="text-center"><span class="fontstyle1">Interested part
 ies are cordially invited.</span> <br /> </p>
LOCATION:
END:VEVENT
BEGIN:VEVENT
UID:calendarize-construction-of-r-harmonic-maps-to-spheres
DTSTAMP:20260409T104958Z
DTSTART:20260416T123000Z
DTEND:20260416T133000Z
SUMMARY:Construction of r-harmonic maps to spheres
DESCRIPTION:Lecture announcement\n \nAs part of the advanced seminar Analy
 sis/Numerics\nProf Dr Anna Siffert\n(University of Münster )\nabout\nCons
 truction of r-harmonic maps to spheres  \nAbstract: In this talk we presen
 t\, a construction method of r-harmonic maps to spheres.We in particular c
 onstruct an explicit family of stable proper weak biharmonic maps from the
 unit ball.This is joint work with Volker Branding.\nThe lecture will take 
 place on\nThursday\, 16.04.2026 at 14.30 - 15.30 in room W01 1-117\nIntere
 sted parties are cordially invited.\n 
X-ALT-DESC;FMTTYPE=text/html:<h3 class="text-center"><span class="fontstyl
 e0"><strong>Lecture announcement</strong></span></h3>\n<p class="text-cent
 er"> </p>\n<p class="text-center"><span class="fontstyle1">As part of the 
 advanced seminar Analysis/Numerics</span></p>\n<p class="text-center"><str
 ong>Prof Dr Anna Siffert</strong></p>\n<p class="text-center"><span class=
 "fontstyle0"><strong>(University of Münster</strong></span><strong> </str
 ong><span class="fontstyle0"><strong>)</strong></span></p>\n<p class="text
 -center"><span class="fontstyle1">about</span></p>\n<h2 class="text-center
 "><span class="fontstyle0">Construction of r-harmonic maps to spheres</spa
 n> <br> </h2>\n<p class="text-center"><span class="fontstyle0"><strong>Abs
 tract</strong>: </span><span class="fontstyle1">In this talk we present\, 
 a construction method of r-harmonic maps to spheres.<br />We in particular
  construct an explicit family of stable proper weak biharmonic maps from t
 he<br />unit ball.<br />This is joint work with Volker Branding.</span></p
 >\n<p class="text-center">The lecture will take place on</p>\n<p class="te
 xt-center"><strong>Thursday\, 16.04.2026 at 14.30 - 15.30 in room W01 1-11
 7</strong></p>\n<p class="text-center">Interested parties are cordially in
 vited.</p>\n<p class="text-center"><span class="fontstyle1"> </span></p>
LOCATION:
END:VEVENT
BEGIN:VEVENT
UID:calendarize-homological-indices-and-local-riemann-roch-type-theorems
DTSTAMP:20260408T144005Z
DTSTART:20260414T121500Z
DTEND:20260414T134500Z
SUMMARY:Homological indices and local Riemann-Roch type theorems
DESCRIPTION:Lecture announcement\nIn the context of the advanced seminar A
 lgebra/Geometry \nDr Matthias Zach (University of Kaiserslautern)\nabout\n
 Homological indices and local Riemann-Roch type theorems\nA homological in
 dex is the Euler characteristic of a complex of coherent sheaves with fini
 te support. Local Riemann-Roch type theorems relate them to intersection n
 umbers and Chern classes\, i.e. objects of topological nature. In complex 
 analytic singularity theory we can thus use such theorems to compute topol
 ogical invariants by algebraic methods. I will report on the toolbox in th
 e computer algebra system OSCAR which we have made available to this end\,
  from Gröbner bases building on Singular's core functionality up to the W
 -functor for the computation of direct images for the ``derived homologica
 l index''.\n \nTuesday 14.04.2026 at 14:15Room W01 0-015 \n \nInterested p
 arties are cordially invited
X-ALT-DESC;FMTTYPE=text/html:<h2 class="text-center">Lecture announcement<
 /h2>\n<h3 class="text-center">In the context of the advanced seminar Algeb
 ra/Geometry<br> </h3>\n<h3 class="text-center"><i><strong>Dr Matthias Zach
  (University of Kaiserslautern)</strong></i></h3>\n<p class="text-center">
 about</p>\n<h2 class="text-center"><strong>Homological indices and local R
 iemann-Roch type theorems</strong></h2>\n<p class="text-center">A homologi
 cal index is the Euler characteristic of a complex of coherent sheaves wit
 h finite support. Local Riemann-Roch type theorems relate them to intersec
 tion numbers and Chern classes\, i.e. objects of topological nature. In co
 mplex analytic singularity theory we can thus use such theorems to compute
  topological invariants by algebraic methods. I will report on the toolbox
  in the computer algebra system OSCAR which we have made available to this
  end\, from Gröbner bases building on Singular's core functionality up to
  the <strong>W-functor</strong> for the computation of direct images for t
 he ``derived homological index''.</p>\n<p class="text-center"> </p>\n<p cl
 ass="text-center"><strong>Tuesday 14.04.2026 at 14:15<br />Room W01 0-015 
 </strong></p>\n<p class="text-center"> </p>\n<h3 class="text-center"><stro
 ng>Interested parties are cordially invited</strong></h3>
LOCATION:
END:VEVENT
BEGIN:VEVENT
UID:calendarize-effective-faltings-and-galois-actions-on-fundamental-group
 s
DTSTAMP:20251110T162441Z
DTSTART:20251111T113000Z
SUMMARY:Effective Foldings and Galois Actions on Fundamental Groups
DESCRIPTION:Lecture announcement \nAs part of the advanced seminar on alge
 bra/geometry\, will be speaking \nMr David Corwin(Ben Gurion University of
  the Negev\, Israel) \nTuesday 11.11.2025 at 12:30 s.t.in W02 1-148\nTitle
 : Effective Foldings and Galois Actions on Fundamental Groups\nAbstract: W
 e start with the statement of Faltings' Theorem\, which says that analgebr
 aic curve of genus at least 2 has finitely many rational points. Concretel
 y\, thissays that for a sufficiently generic polynomialf(x\,y) with ration
 al coefficients of degree at least 5\, there are finitely many rational pa
 irs(x\,y) in Q^2 such that f(x\,y)=0.The question of provably determining 
 that finite set for a given f (i.e.\, for a given curve)is still wide open
 . I discuss one approach to this question\, involving actions of Galoisgro
 ups on (quotients of) the topological fundamental group of the curve in qu
 estion. Iftime permits\, we discuss the approach of Chabauty and Kim that 
 combines this with p-adic analysis to produce a possibly effective way to 
 bound the set of rational points ona given curve. This approach is the bas
 is for my current work with Martin Lüdtke ofOldenburg.\nInterested partie
 s are cordially invited.
X-ALT-DESC;FMTTYPE=text/html:<h2 class="text-center">Lecture announcement<
 br> </h2>\n<p class="text-center">As part of the advanced seminar on algeb
 ra/geometry\,<br /> will be speaking </p>\n<h3 class="text-center"><i><str
 ong>Mr David Corwin<br>(Ben Gurion University of the Negev\, Israel)</stro
 ng></i><br> </h3>\n<p class="text-center"><strong>Tuesday 11.11.2025 at 12
 :30 s.t.<br />in W02 1-148</strong></p>\n<h2 class="text-center"><br><stro
 ng>Title: Effective Foldings and Galois Actions on Fundamental Groups</str
 ong></h2>\n<p class="text-center"><br />Abstract: We start with the statem
 ent of Faltings' Theorem\, which says that an<br />algebraic curve of genu
 s at least 2 has finitely many rational points. Concretely\, this<br />say
 s that for a sufficiently generic polynomial<br />f(x\,y) with rational co
 efficients of degree at least 5\, there are finitely many rational pairs<b
 r />(x\,y) in Q^2 such that f(x\,y)=0.<br />The question of provably deter
 mining that finite set for a given f (i.e.\, for a given curve)<br />is st
 ill wide open. I discuss one approach to this question\, involving actions
  of Galois<br />groups on (quotients of) the topological fundamental group
  of the curve in question. If<br />time permits\, we discuss the approach 
 of Chabauty and Kim that combines this with p-<br />adic analysis to produ
 ce a possibly effective way to bound the set of rational points on<br />a 
 given curve. This approach is the basis for my current work with Martin Lü
 dtke of<br />Oldenburg.</p>\n<p class="text-center"><br />Interested parti
 es are cordially invited.</p>
LOCATION:
END:VEVENT
END:VCALENDAR