Current Seminars
Upcoming Seminars
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PSDS & EC Joint Seminar: Random Locally Flat-Foldable Origami
Location: SLMath: Eisenbud Auditorium, Online/Virtual Speakers: Corrine Yap (Georgia Institute of Technology)The mathematics of origami, or paper folding, raises rich questions in combinatorics and computational geometry, particularly related to flat-foldability: given a crease pattern, represented as a planar graph, and an assignment of mountains and valleys to the creases, can the configuration fold flat? Perhaps surprisingly, this decision problem for “global” flat-foldability is NP-hard in general. In contrast, “local" flat-foldability (folding flat in a small ball around each vertex) can be characterized by a few simple combinatorial conditions.
In this talk, we’ll present a new probabilistic perspective on flat-foldable origami. We consider the uniform distribution on locally flat-foldable crease patterns and a natural Markov chain called the face-flip chain which approximately samples from this distribution. We prove that this chain mixes rapidly for several natural families of origami tessellations---the square twist, the square grid, and the Miura-ori---as well as for the single-vertex crease pattern. We also show that on the square grid, a random locally flat-foldable configuration is exponentially unlikely to be globally flat-foldable. Joint work with Tom Hull and Marcus Michelen.
Updated on Apr 22, 2025 01:04 PM PDT -
EC Seminar: Symmetrically colored arithmetic progressions, an Erdős--Gyárfás problem for progressions, and uniform sets with few progressions
Location: SLMath: Baker Board Room, Online/Virtual Speakers: Jonathan Tidor (Stanford University)Updated on Apr 23, 2025 02:47 PM PDT -
Chancellor Professor Course: Interdisciplinary Topics in Mathematics: Theory of Combinatorial Limits
Location: UC Berkeley, Dwinelle 183 Speakers: Daniel Kral (Masaryk University; Universität Leipzig)The theory of combinatorial limits is a rapidly developing area of mathematics, which provides analytic tools to study large combinatorial objects (e.g., graphs representing social networks). These analytic methods have led to new ways to cope with notoriously difficult extremal combinatorics questions and established new links between analysis, combinatorics, ergodic theory, group theory, probability theory and statistics. The theory was also the subject of the 2021 Abel Prize lecture of Lovász entitled "Continuous limits of finite structures".
The course will present basic concepts of the theory of combinatorial limits related to various combinatorial objects such as graphs, permutations, and hypergraphs, and discuss analytic representations of their limits. We will discuss how the theory of combinatorial limits is related to regularity decompositions and how its analytic tools can be applied to various problems in computer science and mathematics, in particular, in extremal combinatorics where Razborov's flag algebra method has led to advances on long-standing open problems (with solutions of the Erdős-Rademacher Problem and the Erdős Pentagon Problem being among the first results obtained using the method). We will demonstrate how the flag algebra arguments can be applied both directly and in a computer-assisted way, including non-asymptotic settings, e.g., to compute particular Ramsey numbers.
Updated on Jan 17, 2025 02:01 PM PST -
Graduate Student Seminar Series: Graph Container Methods
Location: SLMath: Eisenbud Auditorium, Online/Virtual Speakers: Robert Krueger (Carnegie Mellon University)I will introduce the two ideas central to the method of graph containers, pioneered by works of Kleitman--Winston and Sapozhenko. Graph containers are a kind of tool for contour arguments --- for "beating the union bound," so to speak --- finding use in probabilistic combinatorics and statistical physics. We will take as a guiding example Sapozhenko's asymptotic enumeration of the independent sets of the hypercube. Time permitting, I'll discuss some recent variations of the method and some open problems.
Updated on Apr 24, 2025 01:21 PM PDT -
UC Berkeley Combinatorics Seminar: Pipe dream, pattern, and polytope perspectives on alternating sign matrices and plane partitions
Location: UC Berkeley, Evans 891 Speakers: Jessica Striker (North Dakota State University)Alternating sign matrices are certain {0,1,-1}-matrices known to be equinumerous with plane partitions in the totally symmetric self-complementary symmetry class (TSSCPP), but no meaningful bijection is known. In joint work with Daoji Huang, we give such a bijection in the reduced, 1432-avoiding case, using the bijection of Gao and Huang between reduced bumpless pipe dreams and reduced pipe dreams. In joint work with Mathilde Bouvel and Rebecca Smith, we discuss the related notion of key-avoidance in alternating sign matrices. In joint work with Vincent Holmlund, we transform TSSCPPs to {0,1,-1}-matrices we call magog matrices, and investigate their enumerative and geometric properties.
Updated on Apr 24, 2025 08:33 AM PDT -
PSDS Seminar: Efficient Sampling and Parameter Estimation for Mallows Models via Metric Learning
Location: SLMath: Eisenbud Auditorium, Online/Virtual Speakers: Yeganeh Alimohammadi (University of California, Berkeley)Models of preference and ranking aim to capture patterns of ordered structure arising across diverse contexts—from voting and recommendation systems to genetics and sports competitions, yet they often rely on fixed, pre-specified notions of distance between rankings. In practice, however, rankings differ in context-specific ways, suggesting that it is natural to let the data itself guide the choice of distance. Motivated by this, we study the Mallows model, in which permutations $\pi$ are sampled proportional to $\exp(-\beta d(\pi, \sigma))$, parameterized by a central ranking $\sigma$ and a dispersion parameter $\beta$, where distance function $d$ can be learned from data.
We analyze a general class of distance metrics based on $L_\alpha$ norms, defined as $d_\alpha(\pi, \sigma) = \sum_{i=1}^n |\pi(i) - \sigma(i)|^\alpha$. For any $\alpha \geq 1$ and $\beta > 0$, we develop a Polynomial-Time Approximation Scheme (PTAS) that achieves two main objectives: (i) approximating the partition function $Z_n(\beta, \alpha)$ within a multiplicative factor of $1 \pm \epsilon$, and (ii) efficiently generating samples that are $\epsilon$-close (in total variation distance) to the true distribution. Leveraging these approximations, we propose a computationally efficient Maximum Likelihood Estimation (MLE) algorithm capable of jointly inferring the central ranking, the dispersion parameter, and the optimal distance metric. We validate our methods empirically on datasets from American College Football and Basketball, demonstrating both theoretical rigor and practical effectiveness.
Updated on Apr 24, 2025 12:32 PM PDT -
PSDS Open Problem Session
Location: SLMath: Eisenbud Auditorium Speakers: Roberto Oliveira (Institute of Pure and Applied Mathematics (IMPA))Updated on Feb 28, 2025 08:01 AM PST -
Chancellor Professor Course: Interdisciplinary Topics in Mathematics: Theory of Combinatorial Limits
Location: UC Berkeley, Dwinelle 183 Speakers: Daniel Kral (Masaryk University; Universität Leipzig)The theory of combinatorial limits is a rapidly developing area of mathematics, which provides analytic tools to study large combinatorial objects (e.g., graphs representing social networks). These analytic methods have led to new ways to cope with notoriously difficult extremal combinatorics questions and established new links between analysis, combinatorics, ergodic theory, group theory, probability theory and statistics. The theory was also the subject of the 2021 Abel Prize lecture of Lovász entitled "Continuous limits of finite structures".
The course will present basic concepts of the theory of combinatorial limits related to various combinatorial objects such as graphs, permutations, and hypergraphs, and discuss analytic representations of their limits. We will discuss how the theory of combinatorial limits is related to regularity decompositions and how its analytic tools can be applied to various problems in computer science and mathematics, in particular, in extremal combinatorics where Razborov's flag algebra method has led to advances on long-standing open problems (with solutions of the Erdős-Rademacher Problem and the Erdős Pentagon Problem being among the first results obtained using the method). We will demonstrate how the flag algebra arguments can be applied both directly and in a computer-assisted way, including non-asymptotic settings, e.g., to compute particular Ramsey numbers.
Updated on Jan 17, 2025 02:01 PM PST -
EC Seminar:
Location: SLMath: Eisenbud Auditorium, Online/Virtual Speakers: Jonathan Tidor (Stanford University)Updated on Apr 23, 2025 09:07 AM PDT -
PSDS & EC Joint Seminar
Location: SLMath: Eisenbud Auditorium, Online/VirtualUpdated on Feb 06, 2025 01:34 PM PST -
PSDS Open Problem Session
Location: SLMath: Eisenbud AuditoriumUpdated on Feb 28, 2025 08:02 AM PST -
EC Seminar
Location: SLMath: Eisenbud Auditorium, Online/VirtualUpdated on Feb 06, 2025 01:30 PM PST -
Chancellor Professor Course: Interdisciplinary Topics in Mathematics: Theory of Combinatorial Limits
Location: UC Berkeley, Dwinelle 183 Speakers: Daniel Kral (Masaryk University; Universität Leipzig)The theory of combinatorial limits is a rapidly developing area of mathematics, which provides analytic tools to study large combinatorial objects (e.g., graphs representing social networks). These analytic methods have led to new ways to cope with notoriously difficult extremal combinatorics questions and established new links between analysis, combinatorics, ergodic theory, group theory, probability theory and statistics. The theory was also the subject of the 2021 Abel Prize lecture of Lovász entitled "Continuous limits of finite structures".
The course will present basic concepts of the theory of combinatorial limits related to various combinatorial objects such as graphs, permutations, and hypergraphs, and discuss analytic representations of their limits. We will discuss how the theory of combinatorial limits is related to regularity decompositions and how its analytic tools can be applied to various problems in computer science and mathematics, in particular, in extremal combinatorics where Razborov's flag algebra method has led to advances on long-standing open problems (with solutions of the Erdős-Rademacher Problem and the Erdős Pentagon Problem being among the first results obtained using the method). We will demonstrate how the flag algebra arguments can be applied both directly and in a computer-assisted way, including non-asymptotic settings, e.g., to compute particular Ramsey numbers.
Updated on Jan 17, 2025 02:01 PM PST -
Professional Development Seminar: Jobs in Industry
Location: SLMath: Eisenbud Auditorium, Online/VirtualCreated on Apr 11, 2025 08:14 AM PDT -
Panelist Lunch
Location: SLMath: Baker Board RoomUpdated on Apr 17, 2025 07:49 AM PDT -
PSDS Open Problem Session
Location: SLMath: Baker Board RoomUpdated on Feb 28, 2025 08:01 AM PST -
Chancellor Professor Course: Interdisciplinary Topics in Mathematics: Theory of Combinatorial Limits
Location: UC Berkeley, Dwinelle 183 Speakers: Daniel Kral (Masaryk University; Universität Leipzig)The theory of combinatorial limits is a rapidly developing area of mathematics, which provides analytic tools to study large combinatorial objects (e.g., graphs representing social networks). These analytic methods have led to new ways to cope with notoriously difficult extremal combinatorics questions and established new links between analysis, combinatorics, ergodic theory, group theory, probability theory and statistics. The theory was also the subject of the 2021 Abel Prize lecture of Lovász entitled "Continuous limits of finite structures".
The course will present basic concepts of the theory of combinatorial limits related to various combinatorial objects such as graphs, permutations, and hypergraphs, and discuss analytic representations of their limits. We will discuss how the theory of combinatorial limits is related to regularity decompositions and how its analytic tools can be applied to various problems in computer science and mathematics, in particular, in extremal combinatorics where Razborov's flag algebra method has led to advances on long-standing open problems (with solutions of the Erdős-Rademacher Problem and the Erdős Pentagon Problem being among the first results obtained using the method). We will demonstrate how the flag algebra arguments can be applied both directly and in a computer-assisted way, including non-asymptotic settings, e.g., to compute particular Ramsey numbers.
Updated on Jan 17, 2025 02:01 PM PST -
PSDS & EC Joint Seminar
Location: SLMath: Eisenbud Auditorium, Online/VirtualUpdated on Feb 06, 2025 01:34 PM PST -
PSDS Open Problem Session
Location: SLMath: Eisenbud AuditoriumUpdated on Feb 28, 2025 08:02 AM PST -
EC Seminar
Location: SLMath: Eisenbud Auditorium, Online/VirtualUpdated on Feb 06, 2025 01:30 PM PST -
Graduate Student Seminar Series
Location: SLMath: Eisenbud Auditorium, Online/VirtualUpdated on Feb 06, 2025 01:39 PM PST -
Professional Development Series
Location: SLMath: Baker Board RoomUpdated on Feb 18, 2025 09:36 AM PST -
PSDS Seminar
Location: SLMath: Eisenbud Auditorium, Online/VirtualUpdated on Feb 06, 2025 01:53 PM PST -
PSDS Open Problem Session
Location: SLMath: Eisenbud AuditoriumUpdated on Feb 28, 2025 08:01 AM PST
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ADJOINT 2025
ADJOINT is a yearlong program that provides opportunities for U.S. mathematicians to conduct collaborative research on topics at the forefront of mathematical and statistical research. Participants will spend two weeks taking part in an intensive collaborative summer session at SLMath. The two-week summer session for ADJOINT 2025 will take place June 30 - July 11, 2025 in Berkeley, California. Researchers can participate in either of the following ways: (1) joining ADJOINT small groups under the guidance of some of the nation's foremost mathematicians and statisticians to expand their research portfolio into new areas, or (2) applying to Self-ADJOINT as part of an existing or newly-formed independent research group ((three-to-five participants is preferred) to work on a new or established research project. Throughout the following academic year, the program provides conference and travel support to increase opportunities for collaboration, maximize researcher visibility, and engender a sense of community among participants.
Updated on Apr 04, 2025 12:25 PM PDT
Past Seminars
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Seminar Chancellor Professor Course: Interdisciplinary Topics in Mathematics: Theory of Combinatorial Limits
Updated on Jan 17, 2025 02:01 PM PST -
Seminar UC Berkeley Combinatorics Seminar
Updated on Feb 13, 2025 09:39 AM PST -
Seminar Chancellor Professor Course: Interdisciplinary Topics in Mathematics: Theory of Combinatorial Limits
Updated on Jan 17, 2025 02:01 PM PST -
Seminar Chancellor Professor Course: Interdisciplinary Topics in Mathematics: Theory of Combinatorial Limits
Updated on Jan 17, 2025 02:01 PM PST -
Seminar PSDS Open Problem Session
Updated on Feb 28, 2025 08:01 AM PST -
Seminar PSDS Seminar: Extreme singular values of sparse random bipartite graph
Updated on Apr 16, 2025 06:26 AM PDT -
Seminar UC Berkeley Combinatorics Seminar: Cluster Theory and Combinatorics for Non-Orientable Surfaces
Updated on Apr 09, 2025 09:51 AM PDT -
Seminar PSDS Graduate Student Seminar: Temporal connectivity of Random Geometric Graphs
Updated on Apr 08, 2025 08:59 AM PDT -
Seminar Professional Development Series: Answering (Tough) Interview Questions
Updated on Apr 11, 2025 12:32 PM PDT -
Seminar EC Graduate Student Seminar: Introduction to Polynomial Methods in Combinatorics (via Shift Operators)
Updated on Apr 10, 2025 10:33 AM PDT -
Seminar Chancellor Professor Course: Interdisciplinary Topics in Mathematics: Theory of Combinatorial Limits
Updated on Jan 17, 2025 02:01 PM PST -
Seminar EC Seminar:The Small Quasi-kernel Conjecture
Updated on Apr 09, 2025 03:02 PM PDT -
Seminar PSDS & EC Joint Seminar: Mathematical questions about a physical theory of non-equilibrium order
Updated on Apr 11, 2025 08:44 AM PDT -
Seminar PSDS Graduate Student Seminar Series: Non-constant ground configurations in the disordered ferromagnet
Updated on Apr 04, 2025 11:29 AM PDT -
Seminar Chancellor Professor Course: Interdisciplinary Topics in Mathematics: Theory of Combinatorial Limits
Updated on Jan 17, 2025 02:01 PM PST -
Seminar PSDS Open Problem Session
Updated on Feb 28, 2025 08:01 AM PST -
Seminar PSDS Seminar: Random trees have height times width O(n log n)
Updated on Apr 03, 2025 10:52 AM PDT -
Seminar UC Berkeley Combinatorics Seminar: Algebra meets probability: permutons from pipe dreams via integrable probability
Updated on Apr 03, 2025 11:58 AM PDT -
Seminar EC Seminar: Unbalanced Zarankiewicz problem for bipartite subdivisions
Updated on Apr 03, 2025 09:43 AM PDT -
Seminar EC Seminar: Typical Lipschitz functions on weak expanders
Updated on Apr 03, 2025 09:43 AM PDT -
Seminar Chancellor Professor Course: Interdisciplinary Topics in Mathematics: Theory of Combinatorial Limits
Updated on Jan 17, 2025 02:01 PM PST -
Seminar EC Seminar: An introduction and update on the study of random multiplicative functions
Updated on Apr 03, 2025 09:42 AM PDT -
Seminar EC Seminar: MaxCut, orthonormal representations, and extension complexity of polytopes
Updated on Apr 03, 2025 09:41 AM PDT -
Seminar EC Seminar: Models of global structure
Updated on Apr 03, 2025 09:41 AM PDT -
Seminar PSDS & EC Joint Seminar: On the Graham-Sloane harmonious tree conjecture
Updated on Apr 04, 2025 08:19 AM PDT -
Seminar Chancellor Professor Course: Interdisciplinary Topics in Mathematics: Theory of Combinatorial Limits
Updated on Jan 17, 2025 02:01 PM PST -
Seminar UC Berkeley Combinatorics Seminar: Perfect t-embeddings and Lozenge Tilings
Updated on Mar 26, 2025 03:07 PM PDT -
Seminar PSDS Graduate Student Seminar: Non-constant ground configurations in the disordered ferromagnet
Updated on Mar 25, 2025 03:56 PM PDT -
Seminar Professional Development Series
Updated on Feb 18, 2025 09:36 AM PST -
Seminar EC Seminar: The structure of hypergraph Tur\'an densities
Updated on Mar 28, 2025 11:04 AM PDT