# Mathematical Sciences Research Institute

Home > Scientific > Colloquia & Seminars

1. # Unlikely intersections in semi-abelian schemes.

Location: 891 Evans Hall
Speakers: Daniel Bertrand (Universite Paris VI)

Given a "non-special" section of a semi-abelian scheme over a curve, the relative Manin-Mumford conjecture (RMM) asserts that its image W meets only finitely many torsion curves. I will explain how a relative version of the points constructed (in a Kummer theoretical setting) by the organizer of this seminar  provide very special" examples of infinite intersection. However, the corresponding curves W recover a "normally special" status, when viewed in the setting of Pink's conjecture on mixed Shimura varieties. Furthermore, these sections form the only counterexample to the standard version of RMM for semi-abelian surfaces. These are joint results with B. Edixhoven, and with D. Masser, A. Pillay and U. Zannier.

Created on Apr 11, 2014 02:11 PM PDT
1. # AT Open Problems/Work in Progress Seminar: Problems arising from an interface between homotopy theory and knot theory.

Location: MSRI: Simons Auditorium
Speakers: Dev Sinha (University of Oregon)

I will survey some mathematics around the application of Goodwillie-Weiss Embedding Calculus to knot theory and some then share some related problems.  These problems (and related comments and questions) include:

- Are the cochains of the n-disks operad formal, say as diagrams of E_infinity algebras?  (This would imply a spectral sequence collapse result, which would in turn imply major results in knot theory and its interface with mathematical physics and Lie theory.  What machinery is there to establish formality of cochains integrally?  Could intersection
theoretic models serve over the integers some of the roles that differential forms play over the reals?)

- Can one explicitly and geometrically define invariants of homotopy classes of maps between say finite complexes which are associated to a bar construction on their cochains over the Koszul dual of the E_infty operad (that is, the derivatives of the identity functor)?  (Rationally, such explicit and geometric "homotopy periods" defined using the bar
construction over the Lie cooperad are a pretty story, useful for applications to geometric questions in which homotopy arises.)

- What are some other consequences of formality of the disks operad, including a strong version in dimension two?  (This is less my direct interest and more something to bring to the attention of people doing things with these operads, including in calculus and factorization homology.  Some like Kontsevich have gotten quite a lot of mileage from this formality over the reals.)

Updated on Apr 17, 2014 04:34 PM PDT
2. # Conformal Field Theory

Location: MSRI: Baker Board Room
Created on Feb 19, 2014 08:18 AM PST
3. # MSRI/Evans Lecture: A journey through motivic integration

Location: 60 Evans Hall
Speakers: François Loeser (Université de Paris VI (Pierre et Marie Curie))

Motivic integration was invented by Kontsevich about 20 years ago for proving that Hodge numbers of Calabi-Yau are birational invariants and has developed at a fast pace since. I will start by presenting informally a device for defining and computing motivic integrals due to Cluckers and myself. I will then focus on  some recent applications. In particular I plan to explain how motivic integration provides tools for proving uniformity results for $p$-adic integrals occuring in the Langlands program and  how one may use "motivic harmonic analysis" to study certain generating series counting curves in enumerative algebraic geometry.

Updated on Apr 11, 2014 03:43 PM PDT
4. # Special day in differential and difference algebra

Location: MSRI: Simons Auditorium
Speakers: Alexandru Buium (University of New Mexico), Lucia Di Vizio (Université Versailles/Saint Quentin-en-Yvelines), James Freitag (University of California, Berkeley), Charlotte Hardouin (Université de Toulouse III (Paul Sabatier)), Rahim Moosa (University of Waterloo), Thomas Scanlon (University of California, Berkeley), Michael Singer (North Carolina State University)

9:30 - 10:20 am: Alexandru Buium (U. New Mexico) Curvature on the integers

Abstract: The talk explains how one can introduce an arithmetic analogue of connection and curvature on principal bundles (over flat space). In the arithmetic  framework functions on manifolds are replaced by integer numbers, partial derivatives  are replaced by Fermat quotients with respect to different primes, and linear connections with values in classical Lie algebras are replaced by non-linear objects naturally attached to the corresponding classical groups.

Our main results are vanishing/non-vanishing theorems for the curvatures of these connections. This is joint work in progress, with Malik Barrett.

10:30 - 11:20 am: James Freitag (UC Berkeley) Superstability and central extensions of algebraic groups

Abstract: Altinel and Cherlin proved that any perfect central extension of an algebraic group over an algebraically closed field which happens to be of finite Morley rank as a group is actually a finite central extension and is itself an algebraic group. We will prove a generalization of their result in the infinite rank setting with an additional hypothesis on the center of the group, while giving an example which shows the necessity of this hypothesis. The inspiration for the work comes from differential algebra; namely, this work answers a question of Cassidy and Singer in the (more general) setting of superstable groups.

11:30 am - 12:20 pm: Rahim Moosa (U. Waterloo) Differential-algebraic tangent spaces and internality to the constants

Abstract: Motivated on the one hand by phenomena in bimeromorphic geometry (so compact complex manifolds) and on the other by model-theoretic consideration arising from the study of the canonical base property, I asked some years ago whether the Kolchin tangent bundle of a finite dimensional differential-algebraic variety has the property that the restriction to any C-algebraic subvariety is C-algebraic. Here C is the field of constants in a saturated differentially closed field of characteristic zero, and C-algebraic means being generically in finite-to-finite correspondence with the C-points of an algebraic variety over C. Actually, one is interested not only in the Kolchin tangent bundle but also its higher order incarnations appearing in the work of Pillay and Ziegler. In recent work with Zoé Chatzidakis and Matthew Harrison-Trainor, we show that while the answer to the question as stated is no, an appropriate generic formulation has a positive answer. I will give motivations for the problem and discuss some aspects of its solution.

2:00 - 2:50 pm: Thomas Scanlon (UC Berkeley)

3:00 - 3:20pm : Tea break

3:20 -4:05pm: Michael Singer (U. North Carolina) Direct and Inverse Problems for Parameterized Linear Differential Equations

Abstract: I will give an introduction to a Galois theory for differential equations of the form Y_x = A(x,t)Y where A(x,t) is an mxm matrix with entries that are functions of the principal variable x and the parameter t . The Galois groups in this theory are linear differential algebraic groups, that is, groups of mxm matrices whose entries are functions of t satisfying some fixed set of differential equations. This theory has been successfully used to decide when solutions of such equations satisfy additional differential equations with respect to the parameters and in particular questions of integrability. I will describe recent work of Minchenko, Ovchinnikov and myself concerning the direct problem calculating the Galois group of a given equation) and the inverse problem (which groups can occur as Galois groups).

4:10 - 4:55pm: Lucia di Vizio (Versailles Saint Quentin) Linear Differential Equations with a discrete parameter: Theory

5:00 - 5:45pm: Charlotte Hardouin (Toulouse) Linear Differential Equations with a discrete parameter: Applications

Common abstract: We will discuss an analogous situation to the one described by M. Singer, apart from the fact that we consider a discrete parameter. In this case the theory produce a Galois group, which is a difference scheme and can be non-\sigma-reduced. We will explain how we get around this difficulty and the implications on the theory.

Updated on Apr 18, 2014 09:01 AM PDT
5. # Eisenbud Seminar: Algebraic Geometry and Commutative Algebra

Location: Evans 939
Speakers: David Berlekamp, David Eisenbud (MSRI - Mathematical Sciences Research Institute)

3:45: David Eisenbud: Assymptotic Boij-Soederberg theory and resolutions over complete intersections of quadrics

I'll describe the cone of resolutions of high syzygies over a complete intersection of quadrics, and other related phenomena.

5:00 David Berlekamp: Castelnuovo-Mumford regularity and log-canonical thresholds

The regularity of an ideal is a measure of its computational complexity.  The log-canonical threshold is a measure of singularity.  Not surprisingly, these things are related - the log-canonical threshold of an ideal sheaf on projective space is (sharply) bounded below by the inverse of its regularity.  This and related bounds are worked out with multiplier ideals in recent work of Kuronya and Pintye.  I will attempt to explain what all of these words mean, and how this is done.

Created on Feb 10, 2014 08:42 AM PST
6. # Berkeley Topology Seminar: Part I: Introductory Talk Equivariant Homotopy and Mackey Functors

Location: 740 Evans Hall
Speakers: Michael Hill (University of Virginia)

I'll describe the computational tools needed to understand the proof of the results in the main talk.

Created on Apr 17, 2014 04:52 PM PDT
7. # Berkeley Topology Seminar: Part II: Main Talk - A variant of Rohlin's Theorem: on eta cubed

Location: 3 Evans Hall
Speakers: Michael Hill (University of Virginia)

Rohlin's theorem on the signature of Spin 4-manifolds can be restated in terms of the connection between real and complex K-theory given by homotopy fixed points. This comes from a bordism result about Real manifolds versus unoriented manifolds, which in turn, comes from a C2-equivariant story. I'll describe a surprising analogue of this for
larger cyclic 2 groups, showing that the element eta cubed is never detected! In particular, for any bordism theory orienting these generalizations of Real manifolds, the three torus is always a boundary.

Created on Apr 17, 2014 04:55 PM PDT
8. # AT Research Seminar Pre-Talk: The Dold-Kan correspondence and commutative monoids

Location: MSRI: Simons Auditorium
Speakers: Birgit Richter (Universität Hamburg)

Over a field in characteristic zero commutative dgas are well-behaved; otherwise they are not. For instance there isn't a
right-induced model structure on them in the general case. I'll explain some of these issues and advertise symmetric sequences to repair that defect.

Updated on Apr 17, 2014 04:57 PM PDT
9. # AT Research Seminar: An algebraic model for commutative HZ-algebras.

Location: MSRI: Simons Auditorium
Speakers: Birgit Richter (Universität Hamburg)

Eilenberg-Mac Lane spectra represent singular cohomology and they allow for rather algebraic considerations in stable homotopy theory. Shipley proved that there is a Quillen equivalence between algebras over the Eilenberg-Mac Lane spectrum of the integers, HZ, and differential graded rings. I'll talk about ongoing work with her where we aim at extending her result to commutative HZ-algebras. This builds on a Dold-Kan type theorem for commutative monoids in symmetric sequences.

Updated on Apr 17, 2014 04:58 PM PDT
10. # AT Postdoc Seminar: The Mirror Symmetry Conjecture and Cobordisms

Location: MSRI: Baker Board Room
Speakers: Hiro Tanaka (Harvard University)

This talk--aimed for a general audience of neither topologists nor model theorists--will discuss applications of cobordisms to Kontsevich's mirror symmetry conjecture. We'll begin by stating a rough version of the
conjecture, which builds a bridge between symplectic geometry on one hand, and on the other hand, algebraic geometry over the complex numbers. We then discuss how the theory of cobordisms, which studies when two manifolds can be the boundary of another manifold, sheds light on how to generalize the mirror symmetry conjecture, while giving us information about objects in symplectic geometry. (For example, two Lagrangians related by a compact cobordism are equivalent in the Fukaya category.)

Updated on Apr 17, 2014 05:00 PM PDT
11. # MT Postdoc Seminar

Location: MSRI: Baker Board Room
Updated on Apr 15, 2014 02:45 PM PDT
12. # Alegbraic Topology Open Problems / Work in Progress Seminar

Location: MSRI: Simons Auditorium
Created on Jan 30, 2014 08:23 AM PST
13. # Conformal Field Theory

Location: MSRI: Baker Board Room
Created on Feb 19, 2014 08:18 AM PST
14. # MSRI/Evans Lecture: The (un)reasonable effectiveness of model theory in mathematics

Location: 60 Evans Hall
Speakers: Carol Wood (Wesleyan University)

The talk will be built around  examples of how model theory informs our understanding in areas of mathematics such as algebra, number theory, algebraic geometry and analysis. The model theory behind these applications includes concepts such as compactness, definability, stability and o-minimality. However, we assume  no special expertise in model theory, but rather aim  to illustrate the kinds  of  mathematical questions for which a model theoretical perspective has proven to be useful.

Updated on Apr 15, 2014 11:58 AM PDT
15. # Model Theory, Arithmetic Geometry and Number Theory Seminar

Location: MSRI: Simons Auditorium
Created on Feb 04, 2014 09:06 AM PST
16. # Model Theory, Arithmetic Geometry and Number Theory Seminar

Location: MSRI: Simons Auditorium
Updated on Mar 24, 2014 11:20 AM PDT
17. # Eisenbud Seminar: Algebraic Geometry and Commutative Algebra

Location: Evans 939

3:45pm
Speaker: Zvi Rosen (UC Berkeley)
Title:   Computing Algebraic Matroids

Abstract: Algebraic matroids characterize the combinatorial structure of an algebraic variety. By decorating the matroid with circuit polynomials and base degrees, we capture even more information about the variety and its coordinate projections.  In this talk, we will introduce algebraic matroids, discuss algorithms for their computation, and present some motivating examples.

5:00pm
Speaker: Noah Giansiracusa (UC Berkeley)
Title:  Equations of Tropical Varieties

Abstract: I'll discuss joint work with J.H. Giansiracusa (Swansea) in which we study scheme theory over the tropical semiring T, using the notion of semiring schemes provided by Toen-Vaquie, Durov, or Lorscheid. We define tropical hypersurfaces in this setting and a tropicalization functor that sends closed subschemes of a toric variety over a field with non-archimedean valuation to closed subschemes of the corresponding toric variety over T. Upon passing to the set of \mathbb{T}-valued points this yields Kajiwara-Payne's extended tropicalization functor. We prove that the Hilbert polynomial of any projective subscheme is preserved by our tropicalization functor, so the scheme-theoretic foundations developed here reveal a hidden flatness in the degeneration sending a variety to its tropical skeleton.

Created on Feb 10, 2014 08:42 AM PST
18. # AT Research Seminar Pre-Talk

Location: MSRI: Simons Auditorium
Updated on Mar 06, 2014 02:41 PM PST
19. # AT Research Seminar

Location: MSRI: Simons Auditorium
Created on Feb 14, 2014 08:56 AM PST
20. # MT Postdoc Seminar

Location: MSRI: Simons Auditorium
Created on Feb 06, 2014 09:23 AM PST
21. # AT Postdoc Seminar

Location: MSRI: Simons Auditorium
Speakers: Vesna Stojanoska (Massachusetts Institute of Technology)
Created on Feb 07, 2014 09:36 AM PST
22. # Alegbraic Topology Open Problems / Work in Progress Seminar

Location: MSRI: Simons Auditorium
Created on Jan 30, 2014 08:23 AM PST
23. # Conformal Field Theory

Location: MSRI: Baker Board Room
Created on Feb 19, 2014 08:18 AM PST
24. # Model Theory, Arithmetic Geometry and Number Theory Seminar

Location: MSRI: Simons Auditorium
Created on Feb 04, 2014 09:06 AM PST
25. # Model Theory, Arithmetic Geometry and Number Theory Seminar

Location: MSRI: Simons Auditorium
Updated on Mar 24, 2014 11:23 AM PDT
26. # Eisenbud Seminar: Algebraic Geometry and Commutative Algebra

Location: Evans 939
Created on Feb 10, 2014 08:43 AM PST
27. # AT Research Seminar Pre-Talk

Location: MSRI: Simons Auditorium
Updated on Mar 06, 2014 02:44 PM PST
28. # AT Research Seminar

Location: MSRI: Simons Auditorium
Created on Feb 14, 2014 08:57 AM PST
29. # MT Postdoc Seminar

Location: MSRI: Simons Auditorium
Created on Feb 06, 2014 09:23 AM PST
30. # AT Postdoc Seminar

Location: MSRI: Simons Auditorium
Speakers: Joseph Hirsh (Massachusetts Institute of Technology)
Created on Feb 07, 2014 09:37 AM PST
31. # AT Seminar

Location: MSRI: Simons Auditorium
Speakers: Alexei Kitaev (Kavli Institute for Theoretical Physics)
Created on Apr 14, 2014 09:17 AM PDT
32. # Alegbraic Topology Open Problems / Work in Progress Seminar

Location: MSRI: Baker Board Room
Created on Jan 30, 2014 08:22 AM PST
33. # Conformal Field Theory

Location: MSRI: Baker Board Room
Created on Feb 19, 2014 08:23 AM PST
34. # Model Theory, Arithmetic Geometry and Number Theory Seminar

Location: MSRI: Baker Board Room
Created on Feb 04, 2014 09:05 AM PST
35. # Model Theory, Arithmetic Geometry and Number Theory Seminar

Location: MSRI: Baker Board Room
Updated on Mar 24, 2014 11:31 AM PDT
36. # Eisenbud Seminar: Algebraic Geometry and Commutative Algebra

Location: Evans 939
Created on Feb 10, 2014 08:43 AM PST
37. # AT Research Seminar Pre-Talk

Location: MSRI: Baker Board Room
Updated on Mar 11, 2014 03:18 PM PDT
38. # AT Research Seminar

Location: MSRI: Baker Board Room
Created on Feb 14, 2014 08:57 AM PST
39. # Alegbraic Topology Open Problems / Work in Progress Seminar

Location: MSRI: Simons Auditorium
Created on Jan 30, 2014 08:20 AM PST
40. # Conformal Field Theory

Location: MSRI: Baker Board Room
Created on Feb 19, 2014 08:24 AM PST
41. # Model Theory, Arithmetic Geometry and Number Theory Seminar

Location: MSRI: Simons Auditorium
Created on Feb 04, 2014 08:54 AM PST
42. # Model Theory, Arithmetic Geometry and Number Theory Seminar

Location: MSRI: Simons Auditorium
Updated on Mar 24, 2014 11:32 AM PDT
43. # Eisenbud Seminar: Algebraic Geometry and Commutative Algebra

Location: Evans 939
Created on Feb 10, 2014 08:44 AM PST
44. # AT Research Seminar Pre-Talk

Location: MSRI: Simons Auditorium
Updated on Mar 06, 2014 02:51 PM PST
45. # AT Research Seminar

Location: MSRI: Simons Auditorium
Created on Feb 14, 2014 08:58 AM PST

seminar
1. # SeminarAT Research Seminar: The classification of Taylor towers for functors from based spaces to spectra

Updated on Apr 14, 2014 11:20 AM PDT
2. # SeminarAT Research Seminar Pre-Talk: Module structures on Goodwillie derivatives

Updated on Apr 14, 2014 10:50 AM PDT
3. # SeminarAlgebraic K- and L-theory of groups rings and their applications to topology and geometry, Part II: Main Talk

Created on Apr 14, 2014 11:19 AM PDT
4. # SeminarBerkeley Model Theory Seminar: Higher amalgamation and polygroupoids.

Updated on Apr 11, 2014 02:06 PM PDT
5. # SeminarIntroduction to the middle K-theory of group rings and their relevance in topology, Part One: Introductory Talk

Created on Apr 14, 2014 11:17 AM PDT
6. # SeminarBerkeley Model Theory Seminar: Pseudo Real Closed fields and NTP2

Updated on Apr 11, 2014 02:01 PM PDT
7. # SeminarFinite Structures Seminar

Created on Apr 09, 2014 03:24 PM PDT
8. # SeminarCommutative Algebra and Algebraic Geometry

Created on Apr 14, 2014 11:22 AM PDT
9. # SeminarMT Research Seminar: Tameness and coincidence of dimensions in expansions of the real field

Updated on Apr 11, 2014 01:54 PM PDT
10. # SeminarMT Research Seminar: Torsion free groups definable in o-minimal structures.

Updated on Apr 11, 2014 01:38 PM PDT
11. # SeminarConformal Field Theory

Created on Feb 19, 2014 08:16 AM PST
12. # SeminarAlegbraic Topology Open Problems / Work in Progress Seminar

Created on Jan 30, 2014 08:24 AM PST
13. # SeminarUC Berkeley Model Theory Seminar: Locally definable groups as covers of definable groups.

Created on Apr 04, 2014 10:01 AM PDT
14. # SeminarMT Research Seminar: The Finite Submodel Property and Definability in Classes of Finite Structures.

Updated on Apr 04, 2014 12:57 PM PDT
15. # SeminarMT Research Seminar: On the fundamental complexity of simple theories

Updated on Apr 04, 2014 09:47 AM PDT
16. # SeminarMSRI/Evans Lecture: Sullivan's conjecture and applications to arithmetic

Updated on Apr 01, 2014 03:43 PM PDT
17. # SeminarConformal Field Theory

Created on Feb 19, 2014 08:15 AM PST
18. # SeminarProblem Sessions in Model Theory

Created on Mar 27, 2014 11:58 AM PDT
19. # SeminarAT Postdoc Seminar: Galois equivariance and stable motivic homotopy theory

Updated on Mar 28, 2014 01:16 PM PDT
20. # SeminarMT Postdoc Seminar

Created on Feb 06, 2014 09:21 AM PST
21. # SeminarAT Research Seminar: Compactified string topology

Updated on Mar 28, 2014 12:07 PM PDT
22. # SeminarAT Research Seminar Pre-Talk: Introduction to string topology and to combinatorial models for the moduli space of Riemann surfaces

Updated on Mar 28, 2014 11:41 AM PDT
23. # SeminarUC Berkeley Topology Seminar: On a nilpotence conjecture of J.P. May

Created on Mar 28, 2014 11:25 AM PDT
24. # SeminarUC Berkeley Topology Seminar Intro talk: Prerequisites on ring spectra and nilpotence

Updated on Mar 28, 2014 10:37 AM PDT
25. # SeminarMSRI/Evans Lecture: Bounding the density of rational points on trascendental hypersurfaces via model theory

Updated on Mar 28, 2014 09:53 AM PDT
26. # SeminarMT Research Seminar: Towards a Z/ell analogue of Bogomolov's birational anabelian geometry.

Updated on Mar 28, 2014 09:40 AM PDT
27. # SeminarMT Research Seminar: Deformation of tame sets and additive invariants.

Updated on Mar 28, 2014 09:18 AM PDT
28. # SeminarConformal Field Theory

Created on Feb 19, 2014 08:14 AM PST
29. # SeminarAT Postdoc Seminar: Uses of commutative rings in homotopy theory

Updated on Mar 28, 2014 10:11 AM PDT
30. # SeminarMT Research Seminar: On VC-minimality and variants

Created on Mar 21, 2014 10:23 AM PDT
There are more then 30 past seminars. Please go to Past seminars to see all past seminars.