Enhancing Representation Theory, Noncommutative Algebra And Geometry Through Moduli, Stability And Deformations

Lead Research Organisation: University of Edinburgh
Department Name: Sch of Mathematics

Abstract

The whole is far greater than the sum of its parts: a collection of objects exhibits many deeper structures than can be understood by simply investigating its constituent pieces. Our visual intuition endows us with a remarkably powerful tool to perceive the whole. This is geometry. Nonetheless, our deepest understanding couples this with order, with precision, and with calculation. This is algebra. The two viewpoints, when fused together, seek to explain both small-scale and large-scale behaviour, together, as one. It is often only by combining both perspectives that the most insightful understanding of either can be achieved.

Pioneered by the PI and coIs and others, the last two decades have seen a series of spectacular advances coming from our proposal's three main themes: stability (in representation theory and algebraic geometry), noncommutative deformations and enhancements (in noncommutative algebra and algebraic geometry), and moduli of complexes (Bridgeland stability, inspired by string theory). Each of these has individually resulted in some of the stand-out mathematical achievements of the last two decades. But all are reaching the limit of what they can achieve alone.

To take the next step, and to solve the pressing research questions, requires bringing together these approaches. This is what this Programme Grant will achieve. The PI and coIs, together with the mathematical expertise at our three institutions and the specialist collaboration of many mathematicians nationally and internationally whom we have enlisted, form an inspiring team with a unique expertise and breadth that straddles much of algebra and geometry. We are enthusiastic because we can now see the same structures arising independently and for separate reasons across different parts of mathematics, which suggests the existence of deep hidden connections. The history of science is filled with such examples, such as the discovery of the theory of symmetries (group theory) in mathematics and in quantum physics. Our own work brings several examples: wall-crossing arising independently in representation theory and in algebraic geometry; the use of noncommutative algebra found at the same time in geometric representation theory and the minimal model programme.

Everyone in our team has particular experience of applying their skills in creative and original ways to problems beyond our own specialism. We are therefore motivated not only by the progress that we expect to make on known unanswered questions, but also by the applications that we cannot yet predict. We believe that by pushing forward the mathematical state-of-the-art, and by reaching out to other disciplines, our proposal will maximise its potential, and through this it will shape and influence a broad range of future problems.

Planned Impact

We have extensive plans to maximise the impact of our work in this proposal, within mathematics and more broadly in academia, as well as to the general public and policy makers. We are developing and synthesising exciting new areas in mathematics, many of which are only beginning to be uncovered now, and the potential benefits are substantial.

We envisage there being several different types of impact.

1. Within Pure Mathematics.

This grant will channel the individual expertise accumulated in our three institutions to extend and deepen the connections between algebra, geometry and topology, leading to new areas of research, new points of interaction, and substantial progress on important existing problems. We will host two international conferences, two workshops, and a research school in the UK; in conjunction with our Project Partners IPMU, Toronto, Tsinghua and UIC, we will apply for multiple sources of funding to organise a series of international conferences. This will be a way of reaching, and showcasing, our programme to a broader international audience than otherwise possible.

2. Knowledge Exchange.

We will work to make our research have the greatest possible impact beyond our own disciplines. We will build on our existing industrial relationships and contacts, including with the Innovation Centre for Data Science, DataLab, and the software company Wolfram, through Christian Korff in Glasgow. These relationships will be guided by the development of our research over the duration of the grant, and we will continually be on the lookout for new opportunities. To foster new links, we will host two sandpit events, which will allow us to bring together a broad range of potential users. We have already identified and contacted some potential partners, from the Centre for Signal and Image Processing at the Technology and Innovation Centre (TIC) in Glasgow city centre, to both TechCube and Codebase in Edinburgh. We will learn from previously successful sandpits hosted by the MIGSAA CDT in Edinburgh, and we will ensure that these conversations evolve into a genuine and sustainable two-way interaction.


3. Outreach.

We shall have a wide-ranging public outreach programme focussed around our research and its objectives, aimed at school children (through roadshows - we have experience of creating exhibits already) and the general public (through Science Festivals, social media and other traditional forms of media). We believe this will have a 3-fold effect: in the short term it will increase public awareness of the vitality and importance of mathematics as an end in itself and as the underpinning technology of much of the modern world; in the medium term it will encourage more young people to take up scientific or quantitative professions; and in the long term it will help to drive innovation in the UK economy. We also intend to harness this grant and its scope and vision to promote the case of mathematics to policy makers, at the local, devolved and national level, through our PI and Outreach Officer seeking opportunities to engage in the debate about the role core research plays to the long-term prosperity of our society.

4. The People Pipeline.

As an immediate impact on individuals, this grant will also create a new network of local, national and international collaborations, through our international Project Partners, which will persist well beyond the end of the grant, to the benefit of UK science. It will employ 6 PDRAs and at least 6 PhD students, all of whom will acquire broad mathematical expertise and be given unique training opportunities through our international partners. And through our sandpit events and internships, our PDRAs and PhD students will acquire the intradisciplinary expertise and the outward-facing skills necessary for both successful careers in academia, and the wider economy.

Publications

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Cedó F (2018) Skew left braces of nilpotent type in Proceedings of the London Mathematical Society

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Smoktunowicz A (2020) Combinatorial solutions to the reflection equation in Journal of Algebra

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Smoktunowicz A (2020) Algebraic approach to Rump's results on relations between braces and pre-lie algebras in Journal of Algebra and Its Applications

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Jiang Q (2021) ON THE CHOW THEORY OF PROJECTIVIZATIONS in Journal of the Institute of Mathematics of Jussieu

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Doikou A (2021) Set-theoretic Yang-Baxter & reflection equations and quantum group symmetries in Letters in Mathematical Physics

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Davis D (2021) On subregular slices of the elliptic Grothendieck-Springer resolution in Pure and Applied Mathematics Quarterly

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Smoktunowicz A (2022) On the passage from finite braces to pre-Lie rings in Advances in Mathematics

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Bezrukavnikov R (2022) Monodromic model for Khovanov-Rozansky homology in Journal für die reine und angewandte Mathematik (Crelles Journal)

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Doikou A (2022) From braces to Hecke algebras and quantum groups in Journal of Algebra and Its Applications

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Rota F (2022) The stability manifold of local orbifold elliptic quotients in Journal of the London Mathematical Society

 
Description During the second half of 2019, Wemyss has completed the following preprints on topics related to the grant: "Stability Conditions for 3-fold Flops" with Hirano, "Stability on contraction algebras implies K(p,1)" with August, "Autoequivalences for 3-fold flops: an overview", "Stringy Kähler moduli, mutation and monodromy" with Donovan. Tom Bridgeland produced "Geometry from Donaldson-Thomas invariants" and "Complex surfaces with equivalent derived categories" with Maciocia. Agata Smoktunowicz has written the following papers "Involutive solutions of the Yang-Baxter-like matrix equation -- theory and algorithms" with Andruskiewicz and "From Braces to Hecke algebras & Quantum Groups" with Doikou.

In the period up to early 2021, the Glasgow team wrote the following: Michael Wemyss - "Double bubble plumbings and two-curve flops" (with I. Smith); "Tits cone intersections and applications" (with O. Iyama); "Stability on contraction algebras implies $K(\pi,1)$" (with J. August); "Stringy K\"ahler moduli, mutation and monodromy" (with W. Donovan); "Stability conditions for 3-fold flops" (with Y. Hirano); Wahei Hara - "Classification of Rank Two Weak Fano Bundles on Del Pezzo Threefolds of Degree Four".

In Sheffield, Tom Bridgeland has been working on a class of Riemann-Hilbert problems naturally arising in Donaldson-Thomas theory. These hint at a deep relationship between cluster varieties and spaces of stability conditions. A particular class of examples relates (via the work of Bridgeland-Smith, Fock-Goncharov and Gaiotto-Moore-Neitzke) to moduli spaces of quadratic differentials and local systems on Riemann surfaces. He has published since Jan 2020:
- Allegretti, Dylan G. L.; Bridgeland, Tom The monodromy of meromorphic projective structures. Trans. Amer. Math. Soc. 373 (2020), no. 9, 6321-6367 [This paper studies spaces of projective structures (also known as PGL_2(C) opers) on Riemann surfaces. The holomorphic case is quite classical, but here we allow the structures to have poles. We show that the space of pairs consisting of a Riemann surface with a projective structure with fixed pole orders is parameterised by a space closely related to the spaces of quadratic differentials appearing in the description of stability spaces by Bridgeland-Smith. We also show that the generalised monodromy of such a projective structure lies in the corresponding cluster variety, which following Fock-Goncharov parameterises framed local systems on the surface. This involves understanding the Stokes data of the projective structures at the singularities.]
-Bridgeland, Tom Riemann-Hilbert problems for the resolved conifold. J. Differential Geom. 115 (2020), no. 3, 395-435.\
[Part of a large project aimed at understanding a class of Riemann-Hilbert problems arising naturally in Donaldson-Thomas theory, this paper is concerned with the case arising from DT theory applied to coherent sheaves on the resolved conifold - a simple example of a non-compact Calabi-Yau threefold. We give a complete solution to the Riemann-Hilbert problem in this case using Barnes double and triple gamma functions. In this way we obtain a natural candidate for a non-perturbative topological string partition function for this Calabi-Yau: a particular holomorphic function whose asymptotic expansion reproduces the genus expansion in Gromov-Witten theory.]
- Bridgeland, Tom; Qiu, Yu; Sutherland, Tom Stability conditions and the A2 quiver. Adv. Math. 365 (2020), 107049, 33 pp.
[This paper contains a detailed treatment of the space of stability conditions of the various triangulated categories associated to the A2 quiver: the standard derived category, and the derived category of the d-dimensional Calabi-Yau Ginzburg algebra for d\geq 2. Using the Schwarz triangle theorem we give a complete description of the relevant spaces, and uncover some interesting connections with the structure of the Frobenius manifold associated to this quiver.]
And Tom has written the following papers: arXiv:2006.13059, Complex hyperkähler structures defined by Donaldson-Thomas invariants, Tom Bridgeland, Ian A.B. Strachan, 27 pages; arXiv:2006.10648, On the monodromy of the deformed cubic oscillator, Tom Bridgeland, Davide Masoero, 68 pages

Finally, the Edinburgh team of Bayer, Gordon and Smoktunowicz and postdocs Davis and Jiang have work as follows:
- arXiv:2004.13268 "On subregular slices of the elliptic Grothendieck-Springer resolution" by Davis on the algebraic geometry of the Grothendieck-Springer resolution of Bun_G
- arXiV:2012.10177 "Gaudin Algebras, RSK and Calogero-Moser Cells in Type A" by Gordon (with Brochier and White) on resolving a major case of a conjecture of Bonnafe-Rouquier
-arXiv:2007.09403 "Set theoretic Yang-Baxter & reflection equations and quantum group symmetries" A.Doikou, A. Smoktunowicz, [math-ph],
- arXiv:2007.09403v1 "Algebraic approach to Rump's results on relation between braces and pre-Lie algebras" by A.Smoktunowicz,
- arXiv:2011.07611 "A new formula for Lazard's correspondence for finite braces and pre-Lie algebras" by A. Smoktunowicz,
- arXiv:1804.04106v5"An Appendix to the paper "On skew braces and their ideals"" by A. Smoktunowicz
[As well as the following published - A. Smoktunowicz, L. Vendramin, R. Weston, Combinatorial solutions to the reflection equation, J. Algebra 549 (2020) 268-290; Agata Smoktunowicz, Algebraic approach to Rump's results on relation between braces and pre-Lie algebras,
Journal of Algebra and its Applications, published as ''online ready']

Qingyuan Jiang has been working on Chow groups and derived categories of quot schemes, which are resolutions of degeneracy loci of maps between vector bundles. His previous preprint on a special case, arXiv:1910.06730, has already been applied by a number of authors, e.g. to describe Chow motives of moduli spaces of vector bundles on curves. An article on their derived categories is in preparation. Qingyuan Jiang, On the Chow theory of Quot schemes of locally free quotients, arXiv:2010.10734

Arend Bayer, Sjoerd Beentjes, Soheyla Feyzbakhsh, Georg Hein, Diletta Martinelli, Fatemeh Rezaee, Benjamin Schmidt: The desingularization of the theta divisor of a cubic threefold as a moduli space. arXiv:2011.12240. Submitted for publication. Bayer's work has focussed on extracting geometric consequences from purely categorical data. The preprint on cubic threefolds leads to a new proof of classical Torelli, that a cubic threefold is determined by its cohomology, by studying a moduli space of stable objects in its derived category.

Jointly with co-organizers at UC Santa Barbara, Michigan State and Paris-Saclay, Arend Bayer and Evgeny Shinder (Lecturer at University of Sheffield) are organising a weekly online "Derived seminar" on topics loosely related to derived categories. While featuring some of the most prominent leaders in the field, it also gives a platform for junior speakers to present their work: many of the invited speakers are young post-docs. It regularly attracts an audience of 40-100 participants for each talk.

In the year 2022:

1. Work of Bayer with Perry settled the last open case of a conjecture by Kuznetsov, disproving his claim that certain subcategories of derived categories of certain Fano threefolds are equivalent. Moreover, they proved a modified version of the conjecture, showing their deformation-equivalence. Perhaps the techniques themselves are the most interesting aspect of the paper, which use Lurie's theory of derived algebraic geometry to setup a more satisfactory framework of group actions on categories, and for their associated equivariant categories, in families. Bayer is already exploring new possible applications, a construction of noncommutative abelian surfaces, in discussions with Laura Pertusi and Xiaolei Zhao.

2. Smoktunowicz has shown that there is a one-to-one correspondence between the set of strongly-nilpotent braces and the set of nilpotent pre-Lie rings of cardinality p^{n} for sufficiently large n (p a prime). As an application, by using well known results about correspondence between braces and Hopf-Galois extensions she uses pre-Lie rings to describe Hopf-Galois extensions. the prime radical (the intersection of all prime ideals in given ring) in noncommutative ring theory has some amazing properties-for example it is nil, and can be used to decompose a ring into a semidirect product of prime rings (when we divide the given ring by the prime radical).

3. Gordon, in work with Brochier and White, has now proved the Bonnafé-Rouquier conjecture for all symmetric groups.

4. Two postdocs from the grant have moved/are moving on to three year positions elsewhere: Dougal Davis at the University of Melbourne and Wahei Hara at IPMU. has moved to my ERC grant, and will take up a 3-year position at IPMU in October.
Exploitation Route This will be used by other mathematicians in the field.
Sectors Education