Warwick Mathematics Institute Events
Seminar List Entry | Seminars by subject
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Combinatorics on 21 November 2025 at 14:00 in B3.02,
Speaker: Ritesh Goenka (University of Oxford)
Title: Source localisation in random walks and internal DLA
Abstract: Suppose we observe the final growth cluster of a random growth process, can we reliably recover where it started? We consider this question for the (edge or vertex) trace of the simple random walk on vertex transitive graphs. As we shall see, the answer seems to be closely related to the transience of the random walk. For the simple random walk on Zd, we obtain almost optimal bounds on the probability of correctly identifying the source as d goes to infinity. We will also discuss some variants of the problem, including localisation from an infinite trace and a high accuracy version. Finally, we shall discuss analogous questions and results for internal diffusion limited aggregation (IDLA) on Zd. This talk is based on joint work with Peter Keevash and Tomasz Przybyłowski.
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Number Theory on 24 November 2025 at 15:00 in B3.02
Speaker: Adam Morgan (University of Cambridge)
Title: TBA
Abstract: TBA
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Geometry and Topology on 27 November 2025 at 13:30 in B3.02
Speaker: Jing Tao (University of Oklahoma)
Title: TBA
Abstract: TBA
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COW on 27 November 2025 at 14:00 in B2.02 (Science Block B)
Speaker: Ben Davison (University of Edinburgh)
Title: The topology of the stack of semistable coherent sheaves on a K3 surface
Abstract: Let nu be a Mukai vector for a K3 surface S. When nu is primitive, the moduli space of semistable coherent sheaves (with respect to a generic polarisation) is deformation equivalent to a Hilbert scheme of points on the same K3 surface. This moduli space is smooth, and its Poincaré polynomial is known by Göttsche's formula. The topology of the stack of semistable sheaves is then determined by the topology of this moduli space. By a theorem of Markman, the cohomology is generated by tautological classes.
This talk is about what happens when nu is not primitive. In this case, there are strictly semistables, and the stack is highly singular and "stacky". Nonetheless, using recently developed algebraic structures on the dual of its cohomology, amounting to a kind of quantum group structure on it, we are able to show that certain cohomological invariants that determine this cohomology are unchanged from the case of primitive nu. In particular, we can entirely determine the cohomology of this stack using chi-independence of cohomological BPS invariants (which I will introduce).
Along the way, we identify this BPS cohomology with the image of tautological classes, generalising Markman's theorem, and prove the chi-independence of Gopakumar-Vafa invariants defined à la Maulik-Toda.
This is joint work with Lucien Hennecart, Tasuki Kinjo, Olivier Schiffmann and Eric Vasserot. -
Analysis on 27 November 2025 at 16:00 in B3.02
Speaker: Edward Feireisl (Czech Academy of Sciences, Prague)
Title: Weak and turbulent solutions of the Euler system of gas dynamics
Abstract: The Euler system of gas dynamics does not admit global in time regular
solutions and it is ill posed in the class of weak solutions. We propose
a new selection criterion to identify a (unique) physically relevant
solution. The method is based on a two step selection procedure; the
first step eliminating non-physical solutions, the second identifying
the turbulent solution imposing maximality of the so-called energy defect. -
COW on 27 November 2025 at 16:00 in MS.02
Speaker: Daniel Huybrechts (Bonn)
Title: The period-index problem for hyperkähler varieties
Abstract: Brauer-Severi varieties (so smooth fibrations with projective spaces as fibres) are not Zariski locally trivial. The failure is measured by the associated Brauer class to which two numerical invariants are attached: period and index. The precise relation between the two is unknown but the index is conjectured to be universally bounded by some power of the period. The talk will start with a gentle introduction into the general theory with a survey of things that are known. In the second half I will study the problem for hyperkähler varieties in which case a better bound is expected and in fact can be proved in interesting cases.
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COW on 27 November 2025 at 17:00 in B3.03
Speaker: Jarosław Buczyński (IMPAN)
Title: Three stories of Riemannian and complex projective manifolds
Abstract: Complex projective manifolds and Riemannian manifolds invite you all to participate in their three epic stories. In the first tale, the main character is going to be a complex projective manifold, and as in every story, there will be some action going on. More specifically, the group of invertible complex numbers, or even better, several copies of those, act on the manifold. The spirit of late Andrzej Białynicki-Birula until this day helps us to comprehend what is going on. The second story is a tale of holonomies, it begins with "a long time ago,..." and concludes with "... and the last missing piece of this mystery is undiscovered till this day". The protagonist of this part is a quaternion-Kahler manifold, while the legacy of Marcel Berger is in the background all the time. In the third part we meet legendary distributions, which are subbundles in the tangent bundle of one of our main characters. Among others, distributions can be foliations, or contact distributions, which like yin and yang live on the opposite sides of the world, yet they strongly interact with one another. Ferdinand Georg Frobenius is supervising this third part. Finally, in the epilogue, all the threads and characters so far connect in an exquisite theorem on classification of low dimensional complex projective contact manifolds. In any dimension the analogous classification is conjectured by Claude LeBrun and Simon Salamon, while in low dimensions it is proved by Jarosław Wiśniewski, Andrzej Weber, in a joint work with the narrator.
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Combinatorics on 28 November 2025 at 14:00 in B3.02
Speaker: Vadim Lozin (University of Warwick)
Title: Hereditary properties of graphs
Abstract: The world of hereditary properties (also known as hereditary classes) is rich and diverse. It contains a variety of properties of theoretical or practical importance, such as planar, bipartite, perfect graphs, etc. Thousands of results in the literature are devoted to individual classes and only a few of them analyse the universe of hereditary classes as a whole. In this talk, we focus on results that reveal a structure in this family and on classes that play a critical role in this structure.
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Algebraic Geometry on 03 December 2025 at 15:00 in B3.02
Speaker: Jarek Buczyński (IMPAN, Warsaw)
Title: Secant varieties of toric varieties, multigraded Hilbert scheme, and apolarity
Abstract: Given a smooth projective toric variety X⊂PN, its r-th secant variety is the closure of the union of linear spaces spanned by r distinct points of X. We will present an elementary method to determine if a point of the projective space is in a given secant variety or not. The method is analogous to a classical theory called apolarity lemma. It can be used to describe all point of a secant variety uniformly, including those very special ones that resisted a systematic approach. We also define a secant variety version of the variety of sums of powers, which roughly encode all the possible ways a point can be presented as an element of the secant variety. We analyse its usefulness to study points with large symmetries. In particular, it can be applied to provide lower bounds for the border rank of some interesting tensors.
The talk is primarily based on https://arxiv.org/abs/1910.01944, joint with Weronika Buczyńska, Duke Mathematical Journal. -
Geometry and Topology on 04 December 2025 at 13:30 in B3.02
Speaker: TBA (TBA)
Title: TBA
Abstract: TBA
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Number Theory on 08 December 2025 at 15:00 in B3.02
Speaker: Lasse Grimmelt (University of Cambridge)
Title: TBA
Abstract: TBA
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Geometry and Topology on 11 December 2025 at 13:30 in B3.02
Speaker: Philipp Bader (University of Glasgow)
Title: TBA
Abstract: TBA
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Analysis on 20 November 2025 at 16:00
Speaker: André Guerra (University of Cambridge)
Title: Morse Theory and Differential Inclusions
Abstract: I will begin by giving a brief overview of rigidity and flexibility results in the theory of differential inclusions, a prime example being isometric embeddings. In two dimensions, the rigidity/flexibility of isometric embeddings is closely related to rigidity/flexibility of non-convex solutions to the Monge-Ampère equation. I will then discuss a recent result, obtained with R. Tione, which gives a complete rigidity/flexibility result for solutions of the Monge-Ampère equation in general dimension, as conjectured by Šverák in 1992. The proof relies on Morse theory for non-smooth functions.
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Geometry and Topology on 20 November 2025 at 13:30
Speaker: Sebastian Hensel (LMU Munich)
Title: Dynamics of torus homeomorphisms and the fine curve graph
Abstract: The fine curve graph is a Gromov hyperbolic graph on which the homeomorphism group of a surface acts. In this talk we will discuss joint work with Frédéric Le Roux which relates the surface dynamics of a torus homeomorphism to its action on the fine curve graph. We show in particular that the shape of a “big" rotation set is determined by the fixed points on the Gromov boundary of the graph. A key ingredient is a metric version of the WPD property for the homeomorphism group of the torus.
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Algebraic Geometry on 19 November 2025 at 15:00
Speaker: Stefania Vassiladis (KCL)
Title: Explicit bounds on foliated surfaces and the Poincaré problem
Abstract: We give a solution to the Poincaré Problem, in the formulation of Cerveau and Lins Neto. We obtain a bound on the degree of general leaves of foliations of general type, which is linear in the genus of the leaf. To achieve this, we will introduce the notion of foliation. I will give some examples that show some pathologies that occurs when dealing with foliations, and how to deal with them using adjoint foliated structures.
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Number Theory on 17 November 2025 at 15:00
Speaker: David Hokken (Universiteit Utrecht)
Title: TBA
Abstract: TBA
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Combinatorics on 14 November 2025 at 14:00
Speaker: Natalie Behague (University of Warwick)
Title: On random regular graphs and the Kim-Vu Sandwich Conjecture
Abstract: The random regular graph G_d(n) is selected uniformly at random from all d-regular graphs on n vertices. This model is a lot harder to study than the Erdős-Renyi binomial random graph model G(n, p) as the probabilities of edges being present are not independent. Kim and Vu conjectured that when d ≫ log n it is possible to ‘sandwich’ the random regular graph G_d(n) between two Erdős-Renyi random graphs with similar edge density. A proof of this sandwich conjecture would unify many previous separate hard-won results.
Various authors have proved weaker versions of the sandwich conjecture with incrementally improved bounds on d — the previous state of the art was due to Gao, Isaev and McKay who proved the conjecture for d ≫ (log n)^4. I will sketch our new proof of the full conjecture.
This is joint work with Richard Montgomery and Daniel Il'kovič. -
Analysis on 13 November 2025 at 16:00
Speaker: John Hughes (University of Oxford)
Title: Towards a Taub-Bolt to Taub-NUT via Ricci flow with surgery
Abstract: A conjecture of Holzegel, Schmelzer and Warnick states that there is a Ricci flow with surgery connecting the two Ricci flat metrics Taub-Bolt and Taub-NUT. We will present some recent progress towards proving this conjecture. This includes showing for the first time the existence of a Ricci flow with surgery with local topology change \mathbb{CP}^2\setminus\{ \mathrm{pt}\} \rightarrow \mathbb{R}^4.
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Geometry and Topology on 13 November 2025 at 13:30
Speaker: Will Cohen (University of Cambridge)
Title: Improving acylindrical actions on trees
Abstract: Loosely speaking, an action of a group on a tree is acylindrical if long enough paths must have small stabilisers. Groups admitting such actions form a natural subclass of acylindrically hyperbolic groups, and an interesting feature of acylindrical actions on trees is that many properties of groups are inherited from their vertex stabilisers. In order to make use of this, it is important to have some degree of control over these stabilisers. For example, can we ask for these stabilisers to be finitely generated? Even stronger, if our group is hyperbolic, can we ask for the stabilisers to be quasiconvex?
In this talk, I will introduce acylindrical actions and some stronger and related concepts, and discuss a method known as the Dunwoody—Sageev resolution that we can use to move between these concepts and provide positive answers to the above questions in some cases. -
Number Theory on 10 November 2025 at 15:00
Speaker: Cathy Swaenepoel (Paris Cite)
Title: Prime numbers with an almost prime reverse
Abstract: Let b ≥ 2 be an integer. For any integer n ≥ 0, we call `reverse' of n in base b the integer obtained by reversing the digits of n. The existence of infinitely many prime numbers whose reverse is also prime is an open problem. In this talk, we will present a joint work with Cécile Dartyge and Joël Rivat, in which we show that there are infinitely many primes with an almost prime reverse. More precisely, we show that there exist an explicit integer \Omega_b > 0 and c_b > 0 such that, for at least c_b b^ℓ / ℓ^2 primes p ∈ [b^{ℓ-1},b^ℓ[, the reverse of p has at most \Omega_b prime factors. Our proof is based on sieve methods and on obtaining a result in the spirit of the Bombieri-Vinogradov theorem concerning the distribution in arithmetic progressions of the reverse of prime numbers.
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Combinatorics on 07 November 2025 at 14:00
Speaker: Jeck Lim (University of Oxford)
Title: Sums of algebraic dilates
Abstract: Given a complex number $\lambda$ and a finite set $A$ of complex numbers, how small can the size of the sum of dilate $A + \lambda\cdot A$ be in terms of $|A|$? If $\lambda$ is transcendental, then $|A + \lambda\cdot A|$ grows superlinearly in $|A|$, whereas if $\lambda$ is algebraic, then $|A + \lambda\cdot A|$ only grows linearly in $|A|$. There have been several works in recent years to prove optimal linear bounds in the algebraic case.
In this talk, we answer the above problem in the following general form: if $\lambda_1,\ldots,\lambda_k$ are algebraic numbers, then
$$|A+\lambda_1\cdot A+\dots+\lambda_k\cdot A|\geq H(\lambda_1,\ldots,\lambda_k)|A|-o(|A|)$$
for all finite subsets $A$ of $\mathbb{C}$, where $H(\lambda_1,\ldots,\lambda_k)$ is an explicit constant that is best possible. We will discuss the main tools used in the proof, which include a Frieman-type structure theorem for sets with small sums of dilates, and a high-dimensional notion of density which we call "lattice density". Joint work with David Conlon. -
Analysis on 06 November 2025 at 16:00
Speaker: Adolfo Arroyo Rabasa (Università di Pisa)
Title: On the structure of one-dimensional currents in general metric spaces
Abstract: The theory of currents in Geometric Measure Theory provides a powerful framework for studying generalized oriented surfaces. I will focus on metric currents – a generalization of classical currents introduced by Ambrosio and Kirchheim (after De Giorgi’s ideas) suitable for analysis on spaces without a differential structure. In the context of metric currents, the Flat Chain Conjecture (FCC) proposes the equivalence between metric currents and flat chains in Euclidean space. This conjecture remains open in general, with notable exceptions in the 1-dimensional and top-dimensional cases. In a general metric space, one can re-formulate the FCC as a strong mass approximation property by normal currents.
I will present a novel functional and optimal transport approach to this formulation of the FCC for 1-dimensional currents in general metric spaces. I will discuss how this can be used to prove every metric current can be covered by a current without boundary in a nearly optimal way with respect to the Kantorovic—Rubinstein norm. Finally, arriving to a general Smirnov-type decomposition for metric 1-currents, which allows one to re-direct the study of such currents to the study of SBV curves (or the study of pieces of Lipschitz curves). -
Geometry and Topology on 06 November 2025 at 13:45
Speaker: Islam Foniqi (University of East Anglia)
Title: Submonoid Membership Problems in One-Relator Groups and Monoids, Surface Groups, and Beyond.
Abstract: The word problem for one-relator monoids remains one of the long-standing open questions in combinatorial algebra. One way to approach it is by studying related decision problems, in particular the submonoid membership problem, in both monoids and groups. In this talk, I will discuss how these problems are connected, drawing on classical work by Adian and Guba. I will also highlight the role of embeddings of right-angled Artin groups and trace monoids, which offer useful insights into the structure of these questions. Finally, I will present recent joint results with Robert D. Gray on the submonoid membership problem in surface groups, and in the broader hyperbolic setting.
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Algebraic Geometry on 05 November 2025 at 15:00
Speaker: Thamarai Venkatachalam (University of College London)
Title: Classification of Q-Fano 3-folds
Abstract: TBA
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Number Theory on 03 November 2025 at 15:00
Speaker: Ross Paterson (University of Bristol)
Title: Quadratic Twists as Random Variables
Abstract: For each square-free integer D, and each elliptic curve E, the 2-Selmer groups of E and its quadratic twist E_D naturally live in the same space. We are motivated to study their independence as E varies. We shall present a heuristic in this direction, and some results in support of it.
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Analysis on 30 October 2025 at 16:00
Speaker: Manuel Del Pino (University of Bath)
Title: Compact Equilibria in the Liquid Drop Model
Abstract: This work addresses the liquid drop model, introduced by Gamow in 1930 and Bohr–Wheeler in 1939, to describe the structure of atomic nuclei in nuclear physics. The problem involves finding a surface in three-dimensional space that is critical for a specific energy functional, balancing surface tension and nonlocal repulsion, subject to a volume constraint.
Spherical solutions always exist and minimize the energy for sufficiently small volumes. However, for larger volumes, constructing non-minimizing critical points becomes more challenging. In this study, we present a new class of large-volume solutions, resembling “pearl collars” arranged along an axis in the shape of a large circle, with geometry close to Delaunay’s unduloids—surfaces of constant mean curvature. We also construct non-minimizing solutions with small mass that resemble two nearly identical spheres connected by a narrow neck.
This is collaboration with Mónica Musso, Andrés Zúñiga, and Rupert Frank -
Algebraic Geometry on 29 October 2025 at 15:00
Speaker: David Eisenbud (UC Berkeley)
Title: A survey of (mostly infinite) free resolutions
Abstract: Finite free resolutions, such as those over polynomial rings, have been studied since the late 19th century, and have well-established applications in algebraic geometry. But most modules over most rings have only infinite resolutions. Among other applications, these arise in the study of group cohomology, and, apparently for this reason, a certain class of infinite resolutions were analyzed by John Tate in a groundbreaking paper of 1957. This and a result of Serre's led to the "Serre-Kaplansky" problem, which dominated the field until 1982.
Recently I and others have been investigating these resolutions from a new point of view. I'll explain the old and new conjectures, and give an historical overview of the field. -
Number Theory on 27 October 2025 at 15:00
Speaker: Hung Bui (University of Manchester)
Title: Weighted central limit theorem for central values of L-functions.
Abstract: A classical result of Selberg says that \log|\zeta(1/2 + it)| has a Gaussian limit distribution. We expect the same thing holds for \log|L(1/2, \chi)| for \chi being over the primitive Dirichlet characters modulo q, as q tends to infinity. Proving such a result remains completely out of reach, as it would imply 100% of these central L-values are non-zero, which is a well-known open conjecture. In this talk, I will describe how one can establish a weighted central limit theorem for the central values of Dirichlet L-functions. Under the Generalized Riemann Hypothesis, one can also obtain a weighted central limit theorem for the joint distribution of the central L-values corresponding to twists of two distinct primitive Hecke eigenforms. This is joint work with Natalie Evans, Stephen Lester and Kyle Pratt.
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Combinatorics on 24 October 2025 at 14:00
Speaker: Nemanja Draganić (University of Oxford)
Title: Hamilton cycles in pseudorandom graphs: resilience and approximate decompositions
Abstract: Dirac’s theorem says that every graph with minimum degree at least half the number of its vertices has a Hamilton cycle. In recent decades, attention has turned to whether similar results hold for sparse pseudorandom graphs, which behave like random graphs in their edge distribution but are defined deterministically.
In this talk, I will describe new results giving an optimal version of Dirac’s theorem in this pseudorandom setting. We show that mildly pseudorandom graphs remain Hamiltonian even after deleting about half the edges at each vertex. Moreover, for a d-regular pseudorandom graph, not only does a Hamilton cycle exist, but the graph almost decomposes into them, containing roughly (1 − ε)d / 2 edge-disjoint Hamilton cycles. -
Analysis on 23 October 2025 at 16:00
Speaker: Michele Caselli (Scuola Normale Superiore (Pisa))
Title: Coercivity and Gamma-convergence of the p-energy of sphere-valued Sobolev maps
Abstract: In this talk, we explore the asymptotic behavior of sphere-valued Sobolev maps as their p-energy approaches the critical Sobolev exponent (i.e., the codimension of their singular set). Based on recent work jointly with Mattia Freguglia and Nicola Picenni, we show compactness and Gamma-convergence of the (renormalized) p-energy to the area functional of the suitable dimension. As a corollary, we also recover a classical result by Hardt and Lin on the convergence of the energy densities of p-energy minimizing maps with fixed boundary conditions, as p approaches the critical exponent.
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Geometry and Topology on 23 October 2025 at 13:30
Speaker: Mahan Mj (Tata Institute of Fundamental Research)
Title: Hyperbolic and elliptic commensurations
Abstract: A group G is said to commensurate a subgroup H, if for all g in G, H^g \cap H is of finite index in H and H^g, where H^g denotes the conjugate of H by g. The commensuration action of G on H can be studied dynamically. This gives rise to two extreme behaviors: hyperbolic and elliptic. We will discuss what these mean and survey a range of theorems and conjectures in this context, starting with work of Mostow and Margulis, and coming to the present day.
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Algebraic Geometry on 22 October 2025 at 15:00
Speaker: Hao Zhang (University of Glasgow)
Title: Local forms for the double An quiver and Gopakumar–Vafa invariants
Abstract: This talk concerns the birational geometry of cAn singularities and their curve-counting invariants through noncommutative methods. I introduce generalised GV invariants for crepant partial resolutions and verify Toda’s formula in this setting. Turning to crepant resolutions, I give intrinsic definitions of Type A potentials on the doubled An quiver (with a loop at each vertex). After coordinate changes, these admit a monomialized form and classify all crepant resolutions of cAn, confirming the Brown–Wemyss Realisation Conjecture; an explicit example shows that the Donovan–Wemyss Conjecture fails in the non-isolated case. Building on the correspondence between crepant resolutions and Type A potentials, I give numerical constraints on possible GV tuples and an explicit classification for cA2. Time permitting, I will also mention the n ≤ 3 classification of Type-A loop-free potentials up to isomorphism and derived equivalence. This is based on arXiv:2412.10042 and arXiv:2504.03139.
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Number Theory on 20 October 2025 at 15:00
Speaker: Holly Krieger (University of Cambridge)
Title: Uniformity in arithmetic dynamics
Abstract: The periodic points of a discrete algebraic dynamical system control its local and global dynamical behaviour. When we impose an arithmetic structure on such a system, we do not generally expect periodic points to be rational. The central open conjecture in arithmetic dynamics asks whether this arithmetic structure imposes uniform constraints on the possible periods of points for families of algebraic dynamical systems. In this talk, we will discuss this conjecture, how it generalizes the torsion conjecture—in particular, the celebrated theorems of Mazur and Merel on rational torsion of elliptic curves—and survey some recent progress on and strategies for attacking this problem.
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Combinatorics on 17 October 2025 at 14:00
Speaker: Eoin Hurley (University of Oxford)
Title: Path Factors of Regular Graphs and Linear Arboricity
Abstract: Graph Decomposition problems have seen huge progress in recent years. However most of this progress has been confined to the dense regime.
For example, the linear arboricity conjecture concerns the decomposition of bounded degree graphs into unions of vertex disjoint paths. The conjecture originated in 1980 with Akiyama, Exoo, and Harary and was resolved asymptotically by Alon in the 1990's. However, in spite of much attention an exact resolution remains far away. Indeed, even the problem of finding a single path factor of the correct size was wide open. We find path factors in regular graphs of the correct size (up to a factor of 2) and use this to generate a new kind of bound for the Linear Arboricity Problem.
This talk is based on joint work with Micha Christoph, Nemanja Draganić, António Girão, Lukas Michel, and Alp Müyesser. -
Analysis on 16 October 2025 at 16:00
Speaker: Leonid Parnovski (University College London)
Title: Classical spectral asymptotics with a modern twist
Abstract: The existence of spectral asymptotics of Laplace or Schroedinger operators acting on Riemannian manifolds is a classical problem studied for more than 100 years. It has been known for a long time that obstacles to the existence of spectral asymptotic expansions are periodic and looping trajectories of the geodesic flow. A conjecture formulated in 2016 stated that these trajectories are the only such obstacles. I will discuss the history of this
problem and describe the recent progress: proving this conjecture in special cases, as well as constructing some counterexamples. This is a joint work with Jeff Galkowski (UCL) and Roman Shterenberg (UAB) -
Geometry and Topology on 16 October 2025 at 13:30
Speaker: Davide Spriano (University of Warwick)
Title: Curtains, walls and stable cylinders.
Abstract: In this talk we will discuss a generalization of Sageev’s wallspace construction that allows to study the geometry of certain spaces by combinatorial properties of certain walls. Specifically, we’ll look at the interactions with hyperbolicity and focus on two applications. In CAT(0) spaces, these techniques allow to construct a “universal hyperbolic quotient”, called the curtain model, that is analogous to the curve graph of a surface. When focusing on a space that is already hyperbolic, the construction can be used to improve its fine properties, and in particular we address a conjecture of Rips and Sela and show that residually finite hyperbolic groups admit globally stable cylinders. This is joint work with Petyt and Zalloum.
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Number Theory on 13 October 2025 at 15:00
Speaker: Thomas Bloom (University of Manchester)
Title: TBA
Abstract: TBA
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Seminar on Affine Algebraic Geometry on 13 October 2025 at 14:15
Speaker: Parnashree Ghosh (TIFR Mumbai)
Title: Structure of affine fibrations over Noetherian rings
Abstract: https://warwick.ac.uk/fac/sci/maths/people/staff/marco_schlichting/seminar/
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Combinatorics on 10 October 2025 at 14:00
Speaker: Julia Böttcher (The London School of Economics and Political Science)
Title: Robustness and resilience for spanning graph of bounded degree
Abstract: The well-known conjecture of Bollob\'as, Eldridge, and Catlin states that any $n$-vertex graph with minimum degree of $(1-\frac{1}{\Delta+1})n$ contains any $n$-vertex graph with maximum degree $\Delta$ as a subgraph. This remains open, but the best general condition for all $\Delta$ is still given by a classic theorem of Sauer and Spencer. We prove sparse analogues of this theorem.
In the talk I will provide some background to this problem, survey developments in the past decades and explain what kind of sparse analogues we obtain, which ingredients go into the proofs (spreadness, and the sparse blow-up lemma, among others) and what remains open. -
Seminar on Affine Algebraic Geometry on 09 October 2025 at 14:00
Speaker: Parnashree Ghosh (TIFR Mumbai)
Title: Triviality of A2 fibrations over PID
Abstract: https://warwick.ac.uk/fac/sci/maths/people/staff/marco_schlichting/seminar/
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Algebraic Geometry on 08 October 2025 at 15:00
Speaker: Alessio Cela (Cambridge)
Title: Tangent Bundles and fixed domain curve counts
Abstract: In this talk, I will explain how the non-vanishing of fixed-domain curve counts implies the stability of the tangent bundle TX with respect to the curve class in question. I will then apply this result to establish the vanishing of most Tevelev degrees for Hirzebruch surfaces and compute the remaining cases by relating them to the corresponding invariants of the projective line. Time permitting, I will also explain how to compute the splitting type of the restriction of the tangent bundle of blow-ups of projective space along a general rational curve, via fixed-domain curve counts. This is joint work with Carl Lian.
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Number Theory on 06 October 2025 at 15:00
Speaker: Chris Hughes (University of York)
Title: Discrete moments of the Riemann zeta function
Abstract: I will discuss some new results on moments of zeta'(rho), the derivative of the Riemann zeta function evaluated at the zeta zeros. Despite being a complex function evaluated at complex points, it turns out to be real and positive on average. We will discuss this from both theoretical and heuristic viewpoints.
Click on a title to view the abstract!