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'''
'''When? Where?:''' [https://wiki.math.wisc.edu/index.php/Graduate_Algebraic_Geometry_Seminar_Fall_2024 Link to current semester]
'''When:''' Wednesdays 4:00pm


'''Where:'''Van Vleck B321 '''Pending''' (Fall 2018)
'''Who:''' All undergraduate and graduate students interested in algebraic geometry, commutative algebra, and related fields are welcome to attend.
[[Image:cat.jpg|thumb|220px| | Lizzie the OFFICIAL mascot of GAGS!!]]


'''Who:''' All undergraduate and graduate students interested in algebraic geometry, commutative algebra, and related fields are welcome to attend.
'''Why:''' The purpose of this seminar is to learn algebraic geometry and commutative algebra by giving and listening to talks in an informal setting. Sometimes people present an interesting paper they find. Other times people give a prep talk for the [https://hilbert.math.wisc.edu/wiki/index.php?title=Algebra_and_Algebraic_Geometry_Seminar&redirect=yes Algebraic Geometry Seminar] or present techniques motivated by the [[Applied Algebra Seminar|Applied Algebra seminar]]. Other times people give a series of talks on a topic they have been studying in-depth. Regardless the goal of GAGS is to provide a supportive and inclusive place for all to learn more about algebraic geometry and commutative algebra.


'''Why:''' The purpose of this seminar is to learn algebraic geometry and commutative algebra by giving and listening to talks in a informal setting. Talks are typically accessible to beginning graduate students and take many different forms. Sometimes people present an interesting paper they find. Other times people give a prep talk for the Friday Algebraic Geometry Seminar. Other times people give a series of talks on a topic they have been studying in-depth. Regardless the goal of GAGS is to provide a supportive and inclusive place for all to learn more about algebraic geometry and commutative algebra.
'''How:''' If you want to get emails regarding time, place, and talk topics ('''which are often assigned quite last minute''') add yourself to the gags mailing list: gags@g-groups.wisc.edu by sending an email to gags+subscribe@g-groups.wisc.edu. If you prefer (and are logged in under your wisc google account) the list registration page is [https://groups.google.com/u/2/a/g-groups.wisc.edu/g/gags here].


'''How:'''If you want to get emails regarding time, place, and talk topics ('''which are often assigned quite last minute''') add yourself to the gags mailing list: gags@lists.wisc.edu. The list registration page is [https://admin.lists.wisc.edu/index.php?p=11&l=gags here].
''' Current Organizers: ''' [https://sites.google.com/view/kevindao Kevin Dao], [https://people.math.wisc.edu/~yluo237/ Yu (Joey) Luo], and [https://sites.google.com/view/bmartinova/home Boyana Martinova].  
'''


== Give a talk! ==
== Give a talk! ==
We need volunteers to give talks this semester. If you're interested contact [mailto:juliette.bruce@math.wisc.edu Juliette] or [mailto:moises@math.wisc.edu Moisés], or just add yourself to the list (though in that case we might move your talk later without your permission). Beginning graduate students are particularly encouraged to give a talk, since it's a great way to get your feet wet with the material.
We need volunteers to give talks this semester. If you're interested, follow the link above to the current semester. Beginning graduate students are particularly encouraged to give a talk, since it's a great way to get your feet wet with the material.


== Being an audience member ==
== Being an audience member ==
The goal of GAGS is to create a safe and comfortable space inclusive of all who wish to expand their knowledge of algebraic geometry and commutative algebra. In order to promote such an environment in addition to the standard expectations of respect/kindness all participants are asked to following the following guidelines:
The goal of GAGS is to create a safe and comfortable space inclusive of all who wish to expand their knowledge of algebraic geometry and commutative algebra. In order to promote such an environment in addition to the standard expectations of respect/kindness all participants are asked to following the following guidelines:
* Do Not Speak For/Over the Speaker:
* Do Not Speak For/Over the Speaker.
* Ask Questions Appropriately:
* Ask Questions Appropriately.
 
==The List of Topics that we Made February 2018==
 
On February 21st of the Month of February of The 2018th Year of the Seventh Age of The Sun, the People Present at GAGS Compiled Ye Followinge Liste of Topics They Wished to Hear Aboute:
 
Feel free to edit the list and/or add references to learn this stuff from.
 
* Schubert Calculus, aka how many lines intersect four given lines in three-dimensional space? The answer to this question is prettiest when you think about it as a problem of intersecting subvarieties in the Grassmanian. ''What is the Grassmanian, you say?'' That's probably a talk we should have every year, so you should give it!
 
* Kindergarten GAGA. GAGA stands for Algebraic Geometry - Analytic Geometry. Serre wrote a famous paper explaining how the two are related, and you could give an exposition suitable to kindergardeners.
 
* Katz and Mazur explanation of what a modular form is. What is it?
 
* Kindergarten moduli of curves.
 
* What is a dualizing sheaf? What is a dualizing complex? What is Serre duality? What is local duality? Can local duality help us understand Serre duality?
 
* Generalizations of Riemann - Roch. (Grothendieck - Riemann - Roch? Hirzebruch - Riemann - Roch?)
 
* Hodge theory for babies
 
* What is a Néron model?
 
* What is a crystal? What does it have to do with D-modules? [http://www.math.harvard.edu/~gaitsgde/grad_2009/SeminarNotes/Nov17-19(Crystals).pdf Here's an encouragingly short set of notes on it].
 
* What and why is a dessin d'enfants?
 
* DG Schemes.
 
 
==Ed Dewey's Wish List Of Olde==
 
Back in the day Ed and Nathan made this list of topics they wanted to hear. They all sound super duper cool, but it's also true that they had many years of AG behind their backs, so this list might not be very representative of what the GAGS audience wants to hear bout.
 
Here are the topics we're '''DYING''' to learn about!  Please consider looking into one of these topics and giving one or two GAGS talks.
 
===Specifically Vague Topics===
* D-modules 101: basics of D-modules, equivalence between left and right D-modules, pullbacks, pushforwards, maybe the Gauss-Manin Connection. Claude Sabbah's introduction to the subject could be a good place to start.
 
* Sheaf operations on D-modules (the point is that then you can get a Fourier-Mukai transform between certain O-modules and certain D-modules, which is more or less how geometric Langlands is supposed to work)
 
===Famous Theorems===
 
===Interesting Papers & Books===
* ''Symplectic structure of the moduli space of sheaves on an abelian or K3 surface'' - Shigeru Mukai.
 
* ''Residues and Duality'' - Robin Hatshorne.
** Have you heard of Serre Duality? Would you like to really understand the nuts and bolts of it and its generalizations? If so this book is for you. (You wouldn't need to read the whole book to give a talk ;).)
 
* ''Coherent sheaves on P^n and problems in linear algebra'' - A. A. Beilinson.
** In this two page paper constructs the semi-orthogonal decomposition of the derived category of coherent sheaves on projective space. (This topic is very important, and there are a ton of other resources for this result and the general theory of derived categories.)
 
* ''Frobenius splitting and cohomology vanishing for Schubert varieties'' - V.B. Mehta and A. Ramanathan.
** In characteristic p the fact that (x+y)^p=x^p+y^p means that one has the Frobenius morphism, which sends f to f^p. In this paper the authors introduce the notion of what it means for a variety to be Frobenius split, and use this to prove certain cohomologcal vanishing results for Schubert varieties. Since then Frobenius splitting -- and its related cousins (F-regularity, strong F-regularity, F-purity, etc.) have played large roles in geometry and algebra in characteristic p. This is a good place to get a sense for what kicked all this stuff off!
 
* ''Schubert Calculus'' - S. L. Kleiman and Dan Laksov.
** An introduction to Schubert calculus suitable for those of all ages. I am told the paper essentially only uses linear algebra!
 
* ''Rational Isogenies of Prime Degree'' - Barry Mazur.
** In this paper Mazur classifies all isogenies of rational elliptic curves of prime order. As a result of this he deduces his famous result that the torsion subgroup of an elliptic curve (over Q) is one of 15 abelian groups. This definitely stares into the land of number theory, but certainly would still be of interest to many.
 
* ''Esquisse d’une programme'' - Alexander Grothendieck.
** Originating from a grant proposal in the mid 1980's this famous paper outlines a tantalizing research program, which seeks to tie numerous different areas of math (algebraic geometry, Teichmuller theory, Galois theory, etc.) together. This is where Grothendieck introduced his famous Lego game and dessin d'enfant. While just a research proposal this paper has seemingly inspired a ton of cool math, and will allow you to "blow peoples’ minds". (The original paper is in French, but there are English translations out there.)
 
* ''Géométrie algébraique et géométrie analytique'' - J.P. Serre.
** A projective variety X over the complex numbers has two lives, an algebraic and an analytic, depending on which topology one wishes to work with. That is one can think about X as a complex manifold and work with holomorphic functions or as an algebraic variety and work with regular functions. Hence to any complex projective variety we have two sheaf theories and as a result two cohomology theories. In this famous paper Serre compares these two and shows they are in fact the same. (''Note: This is a super fundamental result that is used all the time; normally in the following way: Uhh... What do you mean by cohomology? Well by GAGA or something it doesn't really mater.) (The original paper is in French, but there are English translations out there.)
 
* ''Limit linear series: Basic theory''- David Eisenbud and Joe Harris.
** One of the more profitable tools -- especially when studying moduli spaces -- in a geometers tool box is the theory of degenerations. However, sometimes we care about more than just the variety we are degenerating and want to keep track of things like vector/line bundles. In this paper Eisenbud and Harris develop the theory of degenerating a curve together with a linear series. From this they prove a ton of cool results: M_g is of general type for g>24, Brill-Noether theory, etc.
 
* ''Picard Groups of Moduli Problems'' - David Mumford.
** This paper is essentially the origin of algebraic stacks.
 
* ''The Structure of Algebraic Threefolds: An Introduction to Mori's Program'' - Janos Kollar
** This paper is an introduction to Mori's famous ``minimal model'' program, which is a far reaching program seeking to understand the birational geometry of higher dimensional varieties.
 
* ''Cayley-Bacharach Formulas'' - Qingchun Ren, Jürgen Richter-Gebert, Bernd Sturmfels.
** A classical result we all learn in a first semester of algebraic geometry is that 5 points in the plane (in general position) determine a unique plane conic. One can similarly show that 9 (general) points in the plane determine a unique plane cubic curve. This paper tries to answer the question: ``What is equation for this cubic curve?''.
 
* ''On Varieties of Minimal Degree (A Centennial Approach)'' - David Eisenbud and Joe Harris.
** Suppose X is a projective variety embedded in projective space so that X is not contained in any hyperplane. By projecting from general points one can see that the degree of X is at least codim(X)+1. This paper discusses the classification of varieties that achieve this lower degree bound i.e. varieties of minimal degree. This topic is quite classical and the paper seems to contain a nice mixture of classical and modern geometry.
 
* ''The Gromov-Witten potential associated to a TCFT'' - Kevin J. Costello.
** This seems incredibly interesting, but fairing warning this paper has been described as ''highly technical'', which considering it uses A-infinity algebras and the derived category of a  Calabi-Yau seems like a reasonable description. (This paper may be covered in Caldararu's Spring 2017 topics course.)
__NOTOC__
 
== Spring 2017 ==
 
<center>
{| style="color:black; font-size:120%" border="0" cellpadding="14" cellspacing="5"
|-
| bgcolor="#D0D0D0" width="300" align="center"|'''Date'''
| bgcolor="#A6B658" width="300" align="center"|'''Speaker'''
| bgcolor="#BCD2EE" width="300" align="center"|'''Title (click to see abstract)'''
|-
| bgcolor="#E0E0E0"| February 14
| bgcolor="#C6D46E"| Moisés Herradón Cueto
| bgcolor="#BCE2FE"|[[Graduate Algebraic Geometry Seminar#February 14| Fun with commutative groups]]
|-
| bgcolor="#E0E0E0"| February 21
| bgcolor="#C6D46E"| Moisés Herradón Cueto
| bgcolor="#BCE2FE"|[[Graduate Algebraic Geometry Seminar#February 21| <math>\mathcal F</math>un with commutative groups]]
|-
| bgcolor="#E0E0E0"| February 28
| bgcolor="#C6D46E"| Dima Arinkin
| bgcolor="#BCE2FE"|[[Graduate Algebraic Geometry Seminar#February 28| ODEs: algebraic vs analytic vs formal]]
|-
| bgcolor="#E0E0E0"| March 7
| bgcolor="#C6D46E"| Vladimir Sotirov
| bgcolor="#BCE2FE"|[[Graduate Algebraic Geometry Seminar#March 7| Topology of Affine Schemes]]
|-
| bgcolor="#E0E0E0"| March 14
| bgcolor="#C6D46E"| David Wagner
| bgcolor="#BCE2FE"|[[Graduate Algebraic Geometry Seminar#March 14| Derived Quot Schemes]]
|-
| bgcolor="#E0E0E0"| March 21
| bgcolor="#C6D46E"| Mao Li
| bgcolor="#BCE2FE"|[[Graduate Algebraic Geometry Seminar#March 21| D modules in prime characteristic]]
|-
| bgcolor="#E0E0E0"| March 28
| bgcolor="#C6D46E"| Spring break
| bgcolor="#BCE2FE"| Whoo!
|-
| bgcolor="#E0E0E0"| April 4
| bgcolor="#C6D46E"| Rachel Davis
| bgcolor="#BCE2FE"|[[Graduate Algebraic Geometry Seminar#April 4| Introduction to Grothendieck's dessins d'enfants]]
|-
| bgcolor="#E0E0E0"| April 11
| bgcolor="#C6D46E"| Brandon Boggess
| bgcolor="#BCE2FE"|[[Graduate Algebraic Geometry Seminar#April 11| Néron models of elliptic curves]]
|-
| bgcolor="#E0E0E0"| April 18
| bgcolor="#C6D46E"| Soumya Sankar
| bgcolor="#BCE2FE"|[[Graduate Algebraic Geometry Seminar#April 18| Modular forms over arbitrary rings]]
|-
| bgcolor="#E0E0E0"| April 25
| bgcolor="#C6D46E"| Solly Parenti
| bgcolor="#BCE2FE"|[[Graduate Algebraic Geometry Seminar#April 25| The Theory of Heights and the Height of Theories]]
|-
| bgcolor="#E0E0E0"| May 2
| bgcolor="#C6D46E"| No talk today
| bgcolor="#BCE2FE"|[[Graduate Algebraic Geometry Seminar#May 2| Keith Rush is giving a talk at the same time]]
|}
</center>
 
== February 14 ==
<center>
{| style="color:black; font-size:100%" table border="2" cellpadding="10" width="700" cellspacing="20"
|-
| bgcolor="#A6B658" align="center" style="font-size:125%" | '''Moisés Herradón Cueto'''
|-
| bgcolor="#BCD2EE"  align="center" | Title: Fun with commutative groups
|-
| bgcolor="#BCD2EE"  | 
Abstract:
 
My goal is to next week talk about Gerard Laumon's preprint ''Transformation de Fourier généralisée'', which will encapsulate all the Fourier transforms I can name (which for me includes the Fourier transform for D-modules on affine space, the Mellin transform, the Fourier-Mukai transform for abelian varieties and the rare John Mahoney transform between modules on the punctured line and vector spaces with a Z-action) into one crazy package.
 
In order to achieve this altered mental state, we will have to rethink all our preconceptions, and rediscover algebraic groups, make sense of Cartier duality for them, define formal groups along the way, and see how duality of Abelian varieties relates to Cartier duality. If you come to the talk in an already in this altered mental state, then hopefully I'll do some examples that you've been too lazy to work out for yourself.
 
|}                                                                       
</center>
 
== February 21 ==
<center>
{| style="color:black; font-size:100%" table border="2" cellpadding="10" width="700" cellspacing="20"
|-
| bgcolor="#A6B658" align="center" style="font-size:125%" | '''<math>\mathcal F</math>un with commutative groups'''
|-
| bgcolor="#BCD2EE"  align="center" | Title: <math>\mathcal F</math>un with commutative groups
|-
| bgcolor="#BCD2EE"  | 
Abstract:
 
I will talk about how last week's Cartier duality relates to duality for abelian varieties. Then we will see how this allows us to take certain complexes of groups which are self dual, going back to altered mental states which are now derived.
 
If we're going to Fourier transform something, it should be a sheaf, but what is even a sheaf on a complex of groups? Once we see what it should be, I will handwave what the Fourier transform is and give a bunch of concrete examples.
 
|}                                                                       
</center>
 
== February 28 ==
<center>
{| style="color:black; font-size:100%" table border="2" cellpadding="10" width="700" cellspacing="20"
|-
| bgcolor="#A6B658" align="center" style="font-size:125%" | '''Dima Arinkin'''
|-
| bgcolor="#BCD2EE"  align="center" | Title: ODEs: algebraic vs analytic vs formal
|-
| bgcolor="#BCD2EE"  | 
Abstract:
 
Linear ordinary differential equations (or, as they are known geometrically, bundles with connections on Riemann surfaces) can be studied from many directions. In algebraic geometry, the goal is ''to classify'' equations rather than ''to solve'' them. The classification can be
done in different settings: algebraic, analytic, or formal; each setting has its advantages and disadvantages. However, for one of the most
important class of equations (equations with regular singularities aka Fuchsian equations) the three approaches agree, leading to a rich
and beautiful picture. 
 
In my talk, I will sketch the algebraic theory of differential equations, focusing on equations with regular singularities. (I do not expect to have time
for irregular singularities.) The talk is related to my topics course on D-modules, but it does not rely on the topics course.
|}                                                                       
</center>
 
== March 7 ==
<center>
{| style="color:black; font-size:100%" table border="2" cellpadding="10" width="700" cellspacing="20"
|-
| bgcolor="#A6B658" align="center" style="font-size:125%" | '''Vladimir Sotirov'''
|-
| bgcolor="#BCD2EE"  align="center" | Title: Topology of Affine Schemes
|-
| bgcolor="#BCD2EE"  | 
Abstract:
 
I will explain in what sense flat morphisms of (affine) schemes are the correct analogue of open maps of topological spaces, and then use that to explain how surjectivity in the sense of Zariski spectra corresponds to surjectivity of functors of points.
 
|}                                                                       
</center>


== March 14 ==
== New Wish List as of Fall 2024 ==
<center>
This wishlist is based on requests from graduate students (new and old and you are encouraged to add to it!). Don't be intimidated by the list (especially as a new graduate student), a lot of the topics here are advanced. You are always welcome to give a talk on a topic that does not appear on this list. If you are looking for a topic and none of the ones listed below sound compelling to you, you can always reach out to one of the organizers for more ideas!
{| style="color:black; font-size:100%" table border="2" cellpadding="10" width="700" cellspacing="20"
*Topics in Representation Theory. There are many topics one can discussion: explaining Lie algebra representations via Fulton-Harris's book (Lecture 7-9), Brauer theory, the Stone-von Neumann theorem, classification and determination of unitary representations, the Harish-Chandra isomorphism, Borel-Bott-Weil, historical results such as Frobenius determinants. Quiver representations are another topic; there is a well-written book by Ralf Schiffler you could look at for this topic.
|-
*The Riemann-Roch Theorem, its generalizations: Grothendieck-Riemann-Roch, Hirzebruch-Riemann-Roch, and applications.
| bgcolor="#A6B658" align="center" style="font-size:125%" | '''David Wagner'''
*GAGA Theorems and how to use them. Some ideas on important results to talk about can be found [https://en.wikipedia.org/wiki/Algebraic_geometry_and_analytic_geometry#Important_results here]. For some references to look at: the appendix in Hartshorne's Algebraic Geometry, Serre's original GAGA paper, and Neeman's book Algebraic and Analytic Geometry.
|-
*Cohen-Macaulay rings and schemes and variants of this type. A useful topic for those working with "mild singularities". The standard reference for this stuff is the book by Brunz and Herzog, but Eisenbud's Commutative Algebra book also has a lot of things to say about CM rings.
| bgcolor="#BCD2EE" align="center" | Title: Derived Quot Schemes
*Hodge Theory for the working Algebraic Geometer. What is the Hodge decomposition? What is the Hard Lefschetz Theorem? What is the statement of the Hodge conjecture? Dolbeault cohomology?
|-
* Algebraic Curves via Hartshorne Chapter IV. What can be said projective curves of degree d and genus g? How do (did) people study algebraic curves? What are the important facts about curves a working algebraic geometer should know?
| bgcolor="#BCD2EE" | 
*Algebraic Suraces via Hartshorne Chapter V and Beauville's Complex Algebraic Surfaces. What does the birational classification of complex algebraic surfaces look like? How ''should'' we classify objects?
Abstract:
*Vector Bundles on P^n. A good reference for this is "Vector Bundles on Complex Projective Spaces" by Christian Okonek. Interesting points of discussion could inclued any of: Horrock's Criterion for vector bundles, Beilinson's Theorem, splitting of uniform bundles of rank r<n, moduli of stable 2-bundles, constructions of vector bundles on P^n for low values of n, Serre's construction of rank 2 bundles, proof of the Grothendieck-Birkhoff Theorem, and etc. These are all very classical problems / theorems in algebraic geometry and a talk on these topics would make a great expository talk.
*Basics of Moduli: functor of points, representable functors, moduli of curves M_g, moduli of Abelian varieties of dimension g, and why do we care? A reference is Harris and Morrison, but there is the now growing textbook by Jarod Alper titled "Stacks and Moduli". Lots of lots of examples are encouraged.
*What is a syzygy? Compute some minimal free resolutions and tell people about how syzygies can tell you a lot about a curve. The Geometry of Syzygies by David Eisenbud is also a good reference and introduction to this topic.
* Derived categories and the Fourier-Mukai Transform. Introduce derived categories and explain their importance in algebraic geometry e.g. through the Fourier-Mukai transform. The book "Fourier-Mukai Transforms in Algebraic Geometry" by Daniel Huybrechts is a good reference for this stuff, but there is also the notes by Andrei Căldăraru on the Arxiv which are more to the point.
* Introduction to Algebraic Stacks: there are a number of references for this e.g. Alper's notes on Moduli, "Algebraic Stacks" by Tomas L. Gomez, the original paper of Deligne and Mumford titled "The Irreducibility of the Space of Curves of Given Genus", Martin Olsson's book "Algebraic Spaces and Stacks", and so on. Examples would be strongly encouraged over technical details and Alper's notes and/or Gomez's article are the best for this.
*There are many many classes of varieties out there that people are interested -- pick one and it could very well be a talk on its own! Here are a few examples; abelian varieties, secant varieties, tangent varieties, Kazdan-Lutszig varieties, toric varieties, flag varieties, Fano varieties, Prym varieties, and beyond.__NOTOC__


The titular paper of Ciocan-Fontanine & Kapranov constructs a "derived" version of Grothendieck's Quot scheme, whose degree zero truncation is the ordinary Quot scheme, and whose tangent space at each k-point consists higher Ext's. In this talk, we will talk about what is meant by "derived" in modern AG and why you might want a derived Quot scheme. In the remaining time, we will give a (hopefully transparent) description of how CF&K construct RQuot.
=== Wishlists from Days of Yore ===
Wishlists from past years can now be found [[Old GAGS Wish Lists|here]].


|}                                                                       
== Semesters ==
</center>


== March 21 ==
[[Image:newcat.jpg|thumb|220px| Toby the OFFICIAL mascot emeritus of GAGS!!]]
<center>
{| style="color:black; font-size:100%" table border="2" cellpadding="10" width="700" cellspacing="20"
|-
| bgcolor="#A6B658" align="center" style="font-size:125%" | '''Mao Li'''
|-
| bgcolor="#BCD2EE"  align="center" | Title: D-modules in prime characteristic
|-
| bgcolor="#BCD2EE"  | 
Abstract:


The usual theory of D-modules concerns itself with sheaves and varieties over complex numbers. In this talk I'm going to consider its characteristic p analogue. The new feature is that the ring of differential operators has a large center. By using this extra information we can give a more precise description about the ring of differential operators, namely it has a canonical structure of an Azumaya algebra over the twisted cotangent bundle. This has lots of applications in algebraic geometry and representation theory.  
[https://wiki.math.wisc.edu/index.php/Graduate_Algebraic_Geometry_Seminar_Spring_2025 Spring 2025]


|}                                                                       
[https://wiki.math.wisc.edu/index.php/Graduate_Algebraic_Geometry_Seminar_Fall_2024 Fall 2024]
</center>


== April 4 ==
[https://wiki.math.wisc.edu/index.php/Graduate_Algebraic_Geometry_Seminar_Spring_2024 Spring 2024]
<center>
{| style="color:black; font-size:100%" table border="2" cellpadding="10" width="700" cellspacing="20"
|-
| bgcolor="#A6B658" align="center" style="font-size:125%" | '''Rachel Davis'''
|-
| bgcolor="#BCD2EE"  align="center" | Introduction to Grothendieck's dessins d'enfants
|-
| bgcolor="#BCD2EE"  | 
In 1978 Bely&#301; first announced the following theorem: every algebraic curve defined over a fixed algebraic closure of the rationals can be represented as a covering of the projective line ramified over at most three points. Deligne then studied the fundamental group of the projective line minus three points. Grothendieck introduced combinatorial structures called dessins d'enfants. One consequence of Bely&#301;'s theorem is that the Galois action on the fundamental group of the projective line minus three points is faithful.  
|}                                                                       
</center>


== April 11 ==
[https://wiki.math.wisc.edu/index.php/Graduate_Algebraic_Geometry_Seminar_Fall_2023 Fall 2023]
<center>
{| style="color:black; font-size:100%" table border="2" cellpadding="10" width="700" cellspacing="20"
|-
| bgcolor="#A6B658" align="center" style="font-size:125%" | '''Brandon Boggess'''
|-
| bgcolor="#BCD2EE"  align="center" | Title: Néron models of elliptic curves
|-
| bgcolor="#BCD2EE"  | 
Abstract:  


We will attempt to do algebraic geometry over the integers. Doing this for elliptic curves will lead us to the idea of Néron models, and we will see how to get our hands on these guys explicitly.
[https://wiki.math.wisc.edu/index.php/Graduate_Algebraic_Geometry_Seminar_Spring_2023 Spring 2023]


|}                                                                       
[https://wiki.math.wisc.edu/index.php/Graduate_Algebraic_Geometry_Seminar_Fall_2022 Fall 2022]
</center>


== April 18 ==
[https://hilbert.math.wisc.edu/wiki/index.php/Graduate_Algebraic_Geometry_Seminar_Spring_2022 Spring 2022]
<center>
{| style="color:black; font-size:100%" table border="2" cellpadding="10" width="700" cellspacing="20"
|-
| bgcolor="#A6B658" align="center" style="font-size:125%" | '''Soumya Sankar'''
|-
| bgcolor="#BCD2EE"  align="center" | Title: Modular forms over arbitrary rings
|-
| bgcolor="#BCD2EE"  | 
Abstract:  


One way to understand moduli spaces of elliptic curves and related moduli problems better, is to study modular forms. With this in mind, I will define modular forms over arbitrary rings in the sense of Katz. I will also talk about p-adic modular forms in the sense of Serre and hopefully motivate the modern treatment of such modular forms.
[https://hilbert.math.wisc.edu/wiki/index.php?title=Graduate_Algebraic_Geometry_Seminar_Fall_2021 Fall 2021]


|}                                                                       
[https://hilbert.math.wisc.edu/wiki/index.php?title=Graduate_Algebraic_Geometry_Seminar_Spring_2021 Spring 2021]
</center>


== April 25 ==
[https://hilbert.math.wisc.edu/wiki/index.php?title=Graduate_Algebraic_Geometry_Seminar_Fall_2020 Fall 2020]
<center>
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| bgcolor="#A6B658" align="center" style="font-size:125%" | '''Solly Parenti'''
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| bgcolor="#BCD2EE"  align="center" | Title: The Theory of Heights and the Height of Theories
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| bgcolor="#BCD2EE"  | 
Abstract:


I will talk about some of the different notions of height in arithmetic geometry, starting from the most naive, ending at some betterer ones.
[https://hilbert.math.wisc.edu/wiki/index.php/Graduate_Algebraic_Geometry_Seminar_Spring_2020 Spring 2020]


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[https://www.math.wisc.edu/wiki/index.php/Graduate_Algebraic_Geometry_Seminar_Fall_2019 Fall 2019]
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[https://www.math.wisc.edu/wiki/index.php/Graduate_Algebraic_Geometry_Seminar_Spring_2019 Spring 2019]


== Organizers' Contact Info ==
[https://www.math.wisc.edu/wiki/index.php/Graduate_Algebraic_Geometry_Seminar_Fall_2018 Fall 2018]
[http://www.math.wisc.edu/~juliettebruce Juliette Bruce]


[https://www.math.wisc.edu/~moises Moisés Herradón Cueto]
[https://www.math.wisc.edu/wiki/index.php/Graduate_Algebraic_Geometry_Seminar_Spring_2018 Spring 2018]


== Past Semesters ==
[https://www.math.wisc.edu/wiki/index.php/Graduate_Algebraic_Geometry_Seminar_Fall_2017 Fall 2017]
[https://www.math.wisc.edu/wiki/index.php/Graduate_Algebraic_Geometry_Seminar_Fall_2017 Fall 2017]


Latest revision as of 10:30, 29 November 2024

When? Where?: Link to current semester

Who: All undergraduate and graduate students interested in algebraic geometry, commutative algebra, and related fields are welcome to attend.

Why: The purpose of this seminar is to learn algebraic geometry and commutative algebra by giving and listening to talks in an informal setting. Sometimes people present an interesting paper they find. Other times people give a prep talk for the Algebraic Geometry Seminar or present techniques motivated by the Applied Algebra seminar. Other times people give a series of talks on a topic they have been studying in-depth. Regardless the goal of GAGS is to provide a supportive and inclusive place for all to learn more about algebraic geometry and commutative algebra.

How: If you want to get emails regarding time, place, and talk topics (which are often assigned quite last minute) add yourself to the gags mailing list: gags@g-groups.wisc.edu by sending an email to gags+subscribe@g-groups.wisc.edu. If you prefer (and are logged in under your wisc google account) the list registration page is here.

Current Organizers: Kevin Dao, Yu (Joey) Luo, and Boyana Martinova.

Give a talk!

We need volunteers to give talks this semester. If you're interested, follow the link above to the current semester. Beginning graduate students are particularly encouraged to give a talk, since it's a great way to get your feet wet with the material.

Being an audience member

The goal of GAGS is to create a safe and comfortable space inclusive of all who wish to expand their knowledge of algebraic geometry and commutative algebra. In order to promote such an environment in addition to the standard expectations of respect/kindness all participants are asked to following the following guidelines:

  • Do Not Speak For/Over the Speaker.
  • Ask Questions Appropriately.

New Wish List as of Fall 2024

This wishlist is based on requests from graduate students (new and old and you are encouraged to add to it!). Don't be intimidated by the list (especially as a new graduate student), a lot of the topics here are advanced. You are always welcome to give a talk on a topic that does not appear on this list. If you are looking for a topic and none of the ones listed below sound compelling to you, you can always reach out to one of the organizers for more ideas!

  • Topics in Representation Theory. There are many topics one can discussion: explaining Lie algebra representations via Fulton-Harris's book (Lecture 7-9), Brauer theory, the Stone-von Neumann theorem, classification and determination of unitary representations, the Harish-Chandra isomorphism, Borel-Bott-Weil, historical results such as Frobenius determinants. Quiver representations are another topic; there is a well-written book by Ralf Schiffler you could look at for this topic.
  • The Riemann-Roch Theorem, its generalizations: Grothendieck-Riemann-Roch, Hirzebruch-Riemann-Roch, and applications.
  • GAGA Theorems and how to use them. Some ideas on important results to talk about can be found here. For some references to look at: the appendix in Hartshorne's Algebraic Geometry, Serre's original GAGA paper, and Neeman's book Algebraic and Analytic Geometry.
  • Cohen-Macaulay rings and schemes and variants of this type. A useful topic for those working with "mild singularities". The standard reference for this stuff is the book by Brunz and Herzog, but Eisenbud's Commutative Algebra book also has a lot of things to say about CM rings.
  • Hodge Theory for the working Algebraic Geometer. What is the Hodge decomposition? What is the Hard Lefschetz Theorem? What is the statement of the Hodge conjecture? Dolbeault cohomology?
  • Algebraic Curves via Hartshorne Chapter IV. What can be said projective curves of degree d and genus g? How do (did) people study algebraic curves? What are the important facts about curves a working algebraic geometer should know?
  • Algebraic Suraces via Hartshorne Chapter V and Beauville's Complex Algebraic Surfaces. What does the birational classification of complex algebraic surfaces look like? How should we classify objects?
  • Vector Bundles on P^n. A good reference for this is "Vector Bundles on Complex Projective Spaces" by Christian Okonek. Interesting points of discussion could inclued any of: Horrock's Criterion for vector bundles, Beilinson's Theorem, splitting of uniform bundles of rank r<n, moduli of stable 2-bundles, constructions of vector bundles on P^n for low values of n, Serre's construction of rank 2 bundles, proof of the Grothendieck-Birkhoff Theorem, and etc. These are all very classical problems / theorems in algebraic geometry and a talk on these topics would make a great expository talk.
  • Basics of Moduli: functor of points, representable functors, moduli of curves M_g, moduli of Abelian varieties of dimension g, and why do we care? A reference is Harris and Morrison, but there is the now growing textbook by Jarod Alper titled "Stacks and Moduli". Lots of lots of examples are encouraged.
  • What is a syzygy? Compute some minimal free resolutions and tell people about how syzygies can tell you a lot about a curve. The Geometry of Syzygies by David Eisenbud is also a good reference and introduction to this topic.
  • Derived categories and the Fourier-Mukai Transform. Introduce derived categories and explain their importance in algebraic geometry e.g. through the Fourier-Mukai transform. The book "Fourier-Mukai Transforms in Algebraic Geometry" by Daniel Huybrechts is a good reference for this stuff, but there is also the notes by Andrei Căldăraru on the Arxiv which are more to the point.
  • Introduction to Algebraic Stacks: there are a number of references for this e.g. Alper's notes on Moduli, "Algebraic Stacks" by Tomas L. Gomez, the original paper of Deligne and Mumford titled "The Irreducibility of the Space of Curves of Given Genus", Martin Olsson's book "Algebraic Spaces and Stacks", and so on. Examples would be strongly encouraged over technical details and Alper's notes and/or Gomez's article are the best for this.
  • There are many many classes of varieties out there that people are interested -- pick one and it could very well be a talk on its own! Here are a few examples; abelian varieties, secant varieties, tangent varieties, Kazdan-Lutszig varieties, toric varieties, flag varieties, Fano varieties, Prym varieties, and beyond.

Wishlists from Days of Yore

Wishlists from past years can now be found here.

Semesters

Toby the OFFICIAL mascot emeritus of GAGS!!

Spring 2025

Fall 2024

Spring 2024

Fall 2023

Spring 2023

Fall 2022

Spring 2022

Fall 2021

Spring 2021

Fall 2020

Spring 2020

Fall 2019

Spring 2019

Fall 2018

Spring 2018

Fall 2017

Spring 2017

Fall 2016

Spring 2016

Fall 2015

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