# Seminars in Pure Mathematics 2013-2018

## 2017-2018 Leicester Pure Mathematics Seminar (Semester 1)

**5/9/2017** Markus Szymik (NTNU Trondheim) "*Symmetry groups of algebraic structures and their homology*"

**Abstract:** The symmetric groups, the general linear groups, and the automorphism groups of free groups are examples of families of groups that arise as symmetry groups of algebraic structures but that are also dear to topologists. There are many other less obvious examples of interest. For instance, in joint work with Nathalie Wahl, this point of view has led to a computation of the homology of the Higman-Thompson groups. It is also key to progress on groups related to mapping class groups and braid groups that I would like to present in this talk.

**3/10/2017** Jan Geuenich (Bielefeld) "*Modulations and potentials for triangulated surfaces*"

**Abstract:** Triangulations of surfaces with marked points and weighted orbifold points encode the mutation combinatorics of "almost all" cluster algebras of finite mutation type. From a representation-theoretic point of view, Jacobian algebras of triangulations play a key role. Daniel Labardini Fragoso defined and investigated these algebras for surfaces without orbifold points. In joint work with him we extend this theory to surfaces that may have weighted orbifold points. The natural set-up for this generalization are modulations for weighted quivers.

**10/10/2017** Greg Stevenson (Glasgow) "*In search of greener pastures*"

**Abstract:** There is an instructive and (miraculously) faithful analogy between commutative rings and tensor triangulated categories. One can speak of prime ideals, the Zariski topology, localization, and the resulting spectra in both contexts and these concepts relate to one another in a way that far exceeds what one would naively, and perhaps reasonably, expect. However, there is trouble in paradise: there is no existing analogue of closed subschemes for tensor triangulated categories and, in particular, residue fields are a problematic concept. I'll discuss joint work with Paul Balmer and Henning Krause which is aimed toward elucidating these elusive residue fields.

**17/10/2017** Stephen Theriault (Southampton) "*Decomposition methods in homotopy theory*"

**Abstract:**The based loops on a topological space has a multiplicative structure which allows it to be decomposed, up to homotopy, as a product of simpler factors, in analogy to how a group may be decomposed as a product. The looping process on a simply-connected space preserves key information, such as all the homotopy groups. In this talk a strategy for decomposing loop spaces will be discussed, and then applied to the interesting case of a simply-connected four-manifold. In particular, we'll show that the homotopy groups of such a manifold can be calculated to the same extent as the homotopy groups of spheres.

**24/10/2017** Julia Goedecke (Leicester) "*Hopf formulae for Tor*"

**Abstract:**A Hopf formula expresses a homology object in terms of a projective presentation, its kernel and certain (generalised) commutators. The first such formula, for second group homology, was given by Hopf in 1942. Over the last 13 years or so, Everaert, Gran, Van der Linden and others have developed Hopf formulae in more general categorical contexts. One of these general contexts is that of a semi-abelian category with a Birkhoff subcategory where the reflector factors through a protoadditive functor. In that generality, some elements of the Hopf formula are necessarily very abstract. With Tim Van der Linden, Guram Donadze and a summer research student Eoghan McDowell, I am studying the special situation of subvarieties of categories of R-modules. It can be seen using properties of algebraic theories that every such subvariety is again a category of modules. Here we can find explicit and easy formulations of the generalised commutators. Since the reflector in this situation turns out to be tensoring, the resulting homology functors are Tor functors.

Through these fairly simple formulations we obtain new ways of calculating, for example, homology of Lie algebras, and Hochschild homology of an associative unital algebra.

More generally, our results apply to any abelian Birkhoff subcategory of any semi-abelian variety, using a factorisation through the abelian core.

**31/10/2017** Karin Baur (Graz) "*Polygon tilings - strand diagrams, permutations and associahedra*"

**Abstract:** Alternating strand diagrams have been introduced by Postnikov in the study of total positivity, Scott has used such diagrams to exhibit a cluster structure on the Grassmannian. In work with P. Martin, we generalised Scott‘s construction to the whole associahedron and have a partial result on counting polygon tilings up to flip equivalence. We recently found a general formula which can be viewed as a Euler-Poincaré formula for the associahedron.

**7/11/2017** Marta Mazzocco (Loughborough) "*Colliding holes in Riemann surfaces*"

**Abstract:** TBA

**14/11/2017** Andrea Solotar (Buenos Aires) "*Gerstenhaber structure of a class of special biserial algebras*"

**Abstract: **For any integer N ≥ 1, we consider a class of self-injective special biserial algebras A_{N} given by quiver and relations over a field k. We study the Gerstenhaber structure of its Hochschild cohomology ring HH^{*}(A_{N}). This Hochschild cohomology ring is a finitely generated k-algebra, due to the results by Snashall and Taillefer. We employ their cohomology computations and Suárez-Álvarez's approach to compute all Gerstenhaber brackets of HH^{*}(A_{N}). Furthermore, we study the Lie algebra structure of the degree-1 cohomology HH^{1}(A_{N}) as embedded into a direct sum of Virasoro algebras and provide a decomposition of HH^{n}(A_{N}) as a module over HH^{1}(A_{N}). (joint work with Van Nguyen, Joanna Meinel, Bregje Pauwels and Maria Julia Redondo)

**21/11/2017** Ben Sharp (Warwick) "*Minimal hypersurfaces in Riemannian manifolds*"

**Abstract:** Minimal hypersurfaces are critical points of the area functional, and the index (of a minimal hypersurface) tells us how many ways one can decrease their area locally; in other words the index measures how unstable a critical point is. Recent works of Marques-Neves prove that closed minimal hypersurfaces exist in abundance, and that their areas and indices are naturally controlled as part of the existence process. This motivates the question “can we classify the set of minimal hypersurfaces in a Riemannian manifold via their indices and areas?”. We will present works which relate the index to the geometry and topology of minimal hypersurfaces. These include separate joint with Lucas Ambrozio-Alessandro Carlotto and Reto Buzano.

**28/11/2017** Yuri Bahturin (Memorial University of Newfoundland, St. John’s) "*Group Gradings on Infinite-dimensional Lie Algebras*"

**Abstract:** We present some methods that enable one to classify gradings by groups on not necessarily associative algebras. There are many results in this area but we will put emphasis on infinite-dimensional associative and Lie algebras. Among these is an important class of complex finitary simple Lie algebras classified by Alexander Baranov.

**5/12/2017** John Barrett (Nottingham) "*The non-commutative geometry of defects"*

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**Abstract:** A non-commutative geometry can be formulated as a real spectral triple, according to Connes. This talk will introduce a diagrammatic calculus for finite real spectral triples (i.e., ones with a finite-dimensional Hilbert space). It provides a quantum invariant of surfaces with spin structure and defect lines. There are two sorts of defect lines, those labelled with the Hilbert space of the non-commutative geometry and those labelled with data that determine a Dirac operator. The axioms of non-commutative geometry follow from the topological properties of defect lines.

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**12/12/2017** Alexander Veselov (Loughborough) "*Lyapunov spectrum of Markov tree*"

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**Abstract:**Markov triples are the integer solutions of the Markov equation x^{2}+y^{2}+z^{2}=3xyz. They surprisingly appeared in many areas of mathematics: initially in classical number theory, but more recently in hyperbolic and algebraic geometry, the theory of Teichmueller spaces and cluster algebras, Frobenius manifolds and Painlevé equations. Markov numbers can be naturally represented using planar binary trees, so their growth depends on the paths on such trees, which can be labelled by the points of real projective line. I will discuss some recent results about the corresponding Lyapunov exponents found jointly with K. Spalding.

## 2017-2018 Leicester Pure Mathematics Seminar (Semester 2)

**16/1/2018** Keomkyo Seo (Sookmyung University, Korea) "*Necessary conditions for submanifolds to be connected in a Riemannian manifold*"

**Abstract:** It is well-known that any simple closed curve in ℝ^{3} bounds at least one minimal disk, which was independently proved by Douglas and Radó. However, for any given two disjoint simple closed curves, we cannot guarantee existence of a compact connected minimal surface spanning such boundary curves in general. From this point of view, it is interesting to give a quantitative description for necessary conditions on the boundary of compact connected minimal surfaces. We derive density estimates for submanifolds with variable mean curvature in a Riemannian manifold with sectional curvature bounded above by a constant. This leads to distance estimates for the boundaries of compact connected submanifolds. As applications, we give several necessary conditions and nonexistence results for compact connected minimal submanifolds, Bryant surfaces, and surfaces with small L^{2} norm of the mean curvature vector in a Riemannian manifold.

## 2016-2017 Leicester Pure Mathematics Seminar (Semester 2)

**31/01/2017** Jelena Grbic (Southampton) "*Homotopy theory of toric objects*"

**Abstract:** At the beginning of this millennium, Toric Topology has been recognised as a new branch of Topology closely related to Algebraic Geometry, Combinatorics and Algebra. Initially problems of Toric Topology were motivated by the study of toric geometry. The approach I take departs from geometry and brings in the tools and techniques of homotopy theory. That allows one to generalise the fundamental concepts of Toric Topology to new ones which will further have applications to geometric group theory, robotics and applied mathematics.

** 07/02/2017** Melanie Rupflin (Oxford) "*Minimal surfaces and geometric flows*"

**Abstract: **The classical Plateau problems has been one of the most influential problems in the development of modern analysis. Posed initially by Lagrange, it asks whether a closed curve in Euclidean space always spans a surfaces with minimal possible area, a question that was answered positively by Douglas and Rado around 1930. In this talk I want to consider some aspects of the classical Plateau Problem and its generalisations and discuss furthermore how one can "flow" to such minimal surfaces by following a suitably defined gradient flow of the Dirichlet energy, i.e. of the integral of gradient squared.

** 14/02/2017** Muneerah Saad Al Nuwairan (King Faisal University) *"The additivity problem"*

**Abstract: ** In our talk, we present the well- known problem in the field of quantum information theory known as “The additivity problem”. It concerns transferring classical information using quantum channels. We will build a mathematical model for the problem, and show that the field of Representation theory provides rich source for solutions. We will also introduce EPOSIC channels, a class of SU(2)-covariant quantum channels that form the extreme points of all SU(2)-irreducibly covariant channels. These channels provide us with a potential solution for the problem.

**22/02/2017** Sebastian del Baño (Queen Mary London) *"Gaussian distributions on affine spaces"*

**Abstract:** We present intrinsic variants of some classical results on real and p-adic Gaussian distributions. Results such as the Isserles-Wick formula for higher moments are considerably simplified by using an intrinsic tensorial approach.

** 28/02/2017** Ilke Canakci (Durham) "*Infinite rank surface cluster algebras*"

**Abstract:** Cluster algebras were introduced by Fomin and Zelevinsky in the context of Lie theory in 2002, however they received much attention since many applications in diverse areas of mathematics have been discovered including quiver representations, Teichmuller theory, integrable systems and string theory. An important class of cluster algebras, called surface cluster algebras, were introduced by Fomin, Shapiro and Thurston by associating cluster algebra structure to triangulated marked surfaces. I will review the state of the art in research associated to surface cluster algebras and report on joint work with Anna Felikson where we introduce a generalisation of surface cluster algebras to infinite rank by associating cluster algebras to surfaces with finitely many accumulation points of boundary marked points.

** 07/03/2017** Nathan Broomhead (Plymouth) "*Thick subcategories, arc-collections and mutation*"

**Abstract:** I will explain some work, in which I describe the lattices of thick subcategories of discrete derived categories. This is done using certain collections of exceptional and sphere-like objects related to non-crossing configurations of arcs in a geometric model.

** 14/03/2017** Tom Bridgeland (Sheffield) "*Wall-crossing and Riemann-Hilbert problems"*

**Abstract:** The subject of the talk will be wall-crossing phenomena for Donaldson-Thomas invariants, but I will only discuss the simplest examples, which are completely concrete. In the first half I will recall the representation theory of the A2 quiver, and explain how the Kontsevich-Soibelman wall-crossing formula works in this case. In the second half I will discuss a natural Riemann-Hilbert problem suggested by the form of the wall-crossing formula, and show how to solve it in the case of the A1 quiver.

** 21/03/2017** Justin Lynd (Aberdeen) "*Fusion systems and classifying spaces"*

**Abstract:** The Martino-Priddy conjecture asserts that two finite groups have equivalent p-completed classifying spaces if and only if their associated fusion systems at the prime p are isomorphic. This was first proved by Bob Oliver in 2004 and 2006. Andrew Chermak generalized this in 2013 by showing that each saturated fusion system over a finite p-group has a unique classifying space attached to it. The proofs of these results depend on the classification of the finite simple groups (CFSG). The focus for this talk will be on the group theoretic aspects of joint work with George Glauberman that helped us remove the dependence of these results on the CFSG. These results concern the question: given a finite group G acting on a finite abelian p-group, when can one find a p-local subgroup H (i.e., a normalizer of a nonidentity p-subgroup) having the same fixed points on the module as does G itself?

** 02/05/2017** Joao Faria Martins (Leeds) "*The fundamental crossed module of the complement of a knotted surface in the 4-sphere"*

**Abstract:** After a review on homotopy 2-types and crossed modules, I will show a method to calculate the homotopy 2-type of the complement of a knotted surface in the 4-sphere given a movie presentation of it. We therefore generalise Wirtinger relations for the fundamental group of a knot complement.

**09/05/2017** Sarah Zerbes (UCL) "*Elliptic curves and the conjecture of Birch--Swinnerton-Dyer"*

**Abstract:** An important problem in number theory is to understand the rational solutions to algebraic equations. One of the first non-trivial examples, cubics in two variables, leads to the theory of so-called elliptic curves. The famous Birch—Swinnerton-Dyer conjecture, one of the Clay Millennium Problems, predicts a relation between the rational points on an elliptic curve and a certain complex-analytic function, the L-function on an elliptic curve. In my talk, I will give an overview of the conjecture and of some new results establishing the conjecture in certain cases.

**22/05/2017** Yann Palu (Picardie) "*Non-kissing complex and tau-tilting over gentle algebras"*

**Abstract:** Gentle algebras form a class of algebras, described in terms of quivers and relations, whose representations are well understood and can be described combinatorially. In this talk, I will introduce a combinatorial notion, called "non-kissing". I will then explain how the non-kissing condition can be interpreted in terms of the representation theory of gentle algebras

## 2016-2017 Leicester Pure Mathematics Seminar (Semester 1)

**04/10/2016** Giuseppe Tinaglia (King's College, London) *"The geometry of constant mean curvature surfaces in Euclidean space"*

**Abstract:** In this talk I will begin by reviewing classical geometric properties of constant mean curvature surfaces, H>0, in R^3. I will then talk about several more recent results for surfaces embedded in R^3 with constant mean curvature, such as curvature and radius estimates for simply-connected surfaces embedded in R^3 with constant mean curvature. Finally I will show applications of such estimates including a characterisation of the round sphere as the only simply-connected surface embedded in R^3 with constant mean curvature and area estimates for compact surfaces embedded in a flat torus with constant mean curvature and finite genus. This is joint work with Meeks.

**11/10/2016** Artie Prendergast-Smith (Loughborough) "*Cones of positive classes"*

**Abstract:** I will explain why convex cones of "positive" cohomology classes arise naturally in algebraic geometry, why they are important, and some things we know about them.

**18/10/2016** Simon Willerton (Sheffield) "*The magnitude of odd balls (From category theory to potential theory)*"

**Abstract:** Tom Leinster defined the notion of the magnitude of a finite metric space, which is some notion of size, using his idea of Euler characteristic of a finite category. You can extend this notion to nice infinite metric spaces such as subsets of Euclidean space. Tom and I conjectured a formula for the magnitude of a convex body involving classical invariants such as volume and surface area, but it turned out to be difficult to calculate precisely for non-trivial bodies. I will explain all of this and how Tony Carbery and Juan-Antonio Barceló recently used potential theory to calculate the magnitude of odd dimensional balls.

**20/10/2016** Neil Ghani (Strathclyde) "*Compositional Game Theory*"

**Abstract:** The central concept of economic game theory is that of Nash Equilibria consisting of a collection of strategies for each player in a game such that no player has a reason to change their strategy assuming all players keep their strategies the same. This talk reports on a new categorical foundation for economic game theory - compositional game theory (CGT). At its core, CGT involves a new representation of games where large games are built from smaller subcomponents of the game. However, while natural from a categorical perspective, developing CGT is no simple matter, eg all current models of game theory are inherently non-compositional! More fundamentally, not all reasoning can be put in the compositional form, especially if there is significant emergent behaviour present in a system which is not present in its subsystems. And, this is certainly the norm in game theory, eg an optimal strategy for a game may not remain optimal when that game is part of a larger network of games.

**8/11/2016** Bob Coecke (Oxford) "*From quantum foundations to natural language meaning via diagrams*"

**Abstract:** This talk concerns how mathematical structures immersing in one discipline can be relevant in an entirely different discipline. The conceptual focus is on structures that enable one to describe interaction. Earlier work on an entirely diagrammatic formulation of quantum theory, which is soon to appear in the form of a textbook [1], has somewhat surprisingly guided us towards an answer for the following question [2, 3]: how do we produce the meaning of a sentence given that we understand the meaning of its words? This work has practical applications in the area of natural language processing, and the resulting tools have meanwhile outperformed existing methods. Recent developments involve the use of several more concepts from quantum theory, for example, density matrices for modelling ambiguity [4] and lexical entailment [5], and convex state spaces to model interaction of psychological concepts [6].

NB: this talk doesn’t require any background in quantum theory, nor in linguistics, nor in category theory

[1] B. Coecke & A. Kissinger (2016, 850 pages) Picturing Quantum Processes. A first course on quantum theory and diagrammatic reasoning. Cambridge University Press.

[2] B. Coecke, M. Sadrzadeh & S. Clark (2010) Mathematical foundations for a compositional distributional model of meaning. arXiv:1003.4394

[3] S. Clark, S., B. Coecke, E. Grefenstette, S. Pulman & M. Sadrzadeh (2013) A quantum teleportation inspired algorithm produces sentence meaning from word meaning and grammatical structure. arXiv:1305.0556.

[4] R. Piedeleu, D. Kartsaklis, B. Coecke & M. Sadrzadeh (2015) Open System Categorical Quantum Semantics in Natural Language Processing. arXiv:1502.00831

[5] D. Bankova, B. Coecke, M. Lewis & D. Marsden (2015): Graded Entailment for Compositional Distributional Semantics. arXiv:1601.04908

[6] J. Bolt, B. Coecke, F. Genovese, M. Lewis, D. Marsden & R. Piedeleu (2016) Interacting Conceptual Spaces. SLPCS. arXiv:1608.01402

**15/11/2016** Giuseppe Tinaglia (King's College, London) "*The geometry of constant mean curvature surfaces in Euclidean space*"

(This talk was postponed from 4 October, see above)

**22/11/2016** Brita Nucinkis (Royal Holloway) "*Classifying spaces for families and their finiteness conditions*"

**Abstract:** I will give a survey on cohomological finiteness conditions for classifying spaces for families of subgroups, such as the dimension or the type and will discuss some old and new questions.

**29/11/2016** Markus Linckelmann (City) "*When do derivations on an algebra yield a simple Lie algebra?*"

**Abstract:** A derivation on an algebra A is a linear endomorphism which satisfies the product rule. The quotient of the space of derivations by the subspace of inner derivations is the first Hochschild cohomology of the algebra A. This is a Lie algebra - and if A is defined over a field of prime characteristic p, then this is a p-restricted Lie algebra. Motivated by questions arising in modular representation theory, we investigate connections between the algebra structure of A and the Lie algebra structure of its first Hochschild cohomology. What are the implications for A if its first Hochschild cohomology is a simple Lie algebra? In joint work with Lleonard Rubio y Degrassi, we answer this question for block algebras of finite groups with one simple module.

**13/12/2016** Peter Jorgensen (Newcastle) "*Thick subcategories of d-abelian categories*" (report on joint work with Martin Herschend and Laertis Vaso)

**Abstract:**Let d be a positive integer. The notion of d-abelian categories was introduced by Jasso. Such a category does not have kernels and cokernels, but rather d-kernels and d-cokernels which are longer complexes with weaker universal properties. Canonical examples of d-abelian categories are d-cluster tilting subcategories of abelian categories. We introduce the notion of thick subcategories of d-abelian categories and show a classification of the thick subcategories of a family of d-abelian categories associated to quivers of type A_n. If time permits, we show how thick subcategories are in bijective correspondence with a particularly nice class of algebra epimorphisms. This generalises a classic result by Geigle and Lenzing.

## 2015-2016 Leicester Pure Mathematics Seminar (Semester 2)

**26/01/2016** Alison Parker (Leeds) Some central idempotents for the Brauer Algebra (abstract)

**09/02/2016** Sian Fryer (Leeds) There And Back Again: A Localization's Tale (abstract)

**16/02/2016** Radha Kessar (City) Ratonality properties for blocks of finite groups (abstract)

**23/02/2016** Michael Whittaker (Glasgow) New directions in self-similar group theory (abstract)

**01/03/2016** Alexander Kasprzyk (Nottingham ) Mirror Symmetry for del Pezzo surfaces (abstract)

**08/03/2016** Stefan Kolb (Newcastle) Universal K-matrix for coideal subalgebras (abstract)

**Thursday 24/03/2016 at 11am** Mark Weber (Macquarie) Vines and internal algebras (abstract)

**Wednesday 20/04/2016 at 1:30pm** Ilke Canakci (Durham) Snake graphs, cluster algebras and continued fractions (abstract)

**26/04/2016** Jing Ping Wang (Kent) Symbolic representation and classification of integrable equations (abstract)

**03/05/2016** Dmitri Gourevich (Valenciennes) Quantum matrix algebras and braided Yangians (abstract)

**10/05/2016** Martin Kalck (Edinburgh) Matrix factorisations: Knörrer’s periodicity and beyond (abstract)

## 2015-2016 Leicester Pure Mathematics Seminar (Semester 1)

**25/08/2015 **Maria Ronco (Universidad de Talca) A regular operad on Dyck paths (abstract)

**22/09/2015** Christine Vespa (Université de Strasbourg) Stable homology of automorphism groups of free groups and functor homology (abstract)

**29/09/2015** (Double Seminar!)

2pm: Martina Balagovic (Newcastle University) Universal K-matrices via quantum symmetric pairs (abstract) (slides)

3pm: James Waldron (Newcastle University) Lie algebroids and differentiable stacks (abstract)

**06/10/2015** James Griffin (Coventry University) The space of circles (abstract) (slides)

**13/10/2015** Szymon Dolecki (Université de Bourgogne) Convergence, compactness, completeness (abstract)

**20/10/2015** André Neves (Imperial College London) Morse index and Geometry (abstract)

**27/10/2015** Ana Rovi (Newcastle University) Lie algebroids in the Loday-Pirashvili category (abstract)

**10/11/2015** Petter Bergh (NTNU, Trondheim) n-angulated categories (abstract)

**17/11/2015** Sira Gratz (Leibniz Universität Hannover) Torsion pairs in discrete cluster categories of Dynkin type A (abstract)

**24/11/2015** Sinead Lyle (University of East Anglia) Semigroup algebras and standard bases (abstract)

**08/12/2015** Ian McIntosh (University of York) Minimal surfaces and their Higgs bundles (abstract)

## 2014-15 Leicester Pure Mathematics Seminar – Semester 2

**03/02/2015 **Peter Topping (University of Warwick) The harmonic map flow revisited abstract

**10/02/2015** Constanze Roitzheim (University of Kent) Model categories- the joy of abstract nonsense abstract

**17/02/2015 **Joanne Leader (University of Leicester) Finite Generation of Ext and (D, A)-stacked Algebras abstract

**24/02/2015 **Jan Boronski (IT4 Innovations, Ostrava) On Birkhoff Attractors and Rotational Chaos abstract

**03/03/2015 **Manolis Georgoulis (University of Leicester) Adaptive numerical methods for the approximation of dynamic singularities abstract

**10/03/2015 **Jamie Vicary (University of Oxford) Higher categories and quantum computation abstract

**17/03/2015 **Michael Singer (University College London) A new approach to monopole metrics abstract

**24/03/2015 **Imma Galvez (Universitat Politecnica de Catalunya)

Incidence (co)algebras and decomposition spaces abstract

**5/05/2015 **Francisco Martin (University of Granada) abstract

Translating solitons of the mean curvature flow

**12/05/2015 **Nicola Gambino (University of Leeds) abstract

Commutative 2-algebra and analytic functors

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## 2014-15 Leicester Pure Mathematics Seminar – Semester 1

**28/08/2014 **Julie Bergner (Univ. of California at Riverside), Homotopical higher categories (Abstract)

**30/09/2014 **Henri Anciaux (Univ. of San Paulo) Marginally trapped submanifolds (Abstract)

**7/10/2014** Gavin Brown (Loughborough University), Pfaffian ideals and Calabi-Yau 3-folds (Abstract)

**14/10/2014 **Andrey Lazarev (Lancaster University) Koszul-Morita duality (Abstract)

**21/10/2014 **Stephane Launois (Univ. of Kent) Efficient recognition of totally nonnegative cells (Abstract)

**28/10/2014 **Samuel Petite (Univ. de Picardie) Simplicity of the homeomorphism group of a tilable lamination (Abstract)

**4/11/2014** Magdalena Rodriguez (Univ. of Granada) Minimal surfaces with finite total curvature and related problems (Abstract)

**11/11/2014** Mike Prest (Univ. of Manchester) Ziegler spectra of domestic string algebras (Abstract)

**18/11/2014** Pavel Tumarkin (Durham Univ.) Coxeter groups, cluster algebras, and geometric manifolds (Abstract)

**25/11/2014 **Ivan Tyukin (University of Leicester) Lyapunov method for unstable attractors (Abstract)

**2/12/2014** 13:30-14:30 Rosie Laking (University of Manchester)

Morphisms in Kb(proj) for a gentle algebra. (Abstract)

15:00-16:00 Joeri Van der Veken (University of Leuven)

Sequences of harmonic maps in the 3-sphere (Abstract)

**9/12/2014 **Jamie Walton (Univ. of York)

Patch frequencies for cut-and-project sets and Diophantine approximation (Abstract)

## 2013-14 Leicester Pure Mathematics Seminar – Semester 2

**28/01/2014 **Ines Henriques (Sheffield), F-thresholds and Test ideals for determinantal ideals of maximal minors (Abstract)

**04/02/2014 **Ralf Schiffler (Conneticut), Positivity in Cluster Algebras (Abstract)

**11/02/2014 **Bruce Bartlett (Oxford), Bordism representation theory in dimension 3 (Abstract)

**18/02/2014 **Jean Fasel (Muenchen), Homotopy groups of algebraic spheres and classification of vector bundles (Abstract)

**25/02/2014 **David Pauksztello (Manchester), An introduction to discrete derived categories (Abstracts)

**04/03/2014 **Ben Sharp (Imperial), Global estimates for harmonic maps form surfaces (Abstract)

**11/03/2014**

**1:30 pm**Ian McIntosh (York), Minimal surfaces and complex quasi-Fuchsian groups (Abstract)

**3 pm**Osbaldo Mata Gutierrez (CIMAT, Guanajuato),

**Subvarieties of the moduli space of vector bundles on a curve (Abstract)**

**18/03/2014 **Karin Erdmann (Oxford), On the generalized Auslander-Reiten condition (Abstract)

**25/03/2014 **Anthony Manning (Warwick) A map of the tetrahedron that describes the sequence of pedal triangles (Abstract)

**06/05/2014** Michael Farber (Warwick), Large Random Spaces and Groups.

**2013-14 Leicester Pure Mathematics Seminar – Semester 1**

**2013-14 Leicester Pure Mathematics Seminar – Semester 1**

**1/10/2013** Anna Felikson (Durham) Cluster algebras of finite mutation type (Abstract)

**08/10/2013** Jan Grabowski (Lancaster) Gradings on cluster algebras and associated combinatorics (Abstract)

**15/10/2013** Joseph Grant (Leeds) Braid group actions and a theorem of Rouquier and Zimmermann (Abstract)

**22/10/2013** Behrang Noohi (Queen Mary) String operations for orbifolds (Abstract)

**29/10/2013 **Ilke Canakci (Leicester) Surface cluster algebra combinatorics via snake graphs(Abstract)

**5/11/2013 **Lynn Heller (Tuebingen) Constrained Willmore Hopf Tori (Abstract)

**12/11/2013** Toby Hall (Liverpool) Digit frequencies for expansions in non-integer bases.(Abstract)

**19/11/2013 **Mark Grant (Newcastle) Lower bounds for the topological complexity of groups(Abstract)

**26/11/2013** Alan Robinson (Warwick) Products and homotopy (Abstract)

**3/12/2013 **Tom Sutherland (Sheffield) Mutation and quadratic differentials (Abstract)

**10/12/2013** Francis Burstall (Bath), Geometry and dynamics of isothermic submanifolds(Abstract)

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