Fri 02 May 16:00: The tectonic, thermal, and temporal controls on the production of critical metal deposits
Abstract not available
- Speaker: Alex Copley
- Friday 02 May 2025, 16:00-17:00
- Venue: Tea Room, Old House.
- Series: Bullard Laboratories Tea Time Talks; organiser: David Al-Attar.
Tue 27 May 14:00: Chromatic Smith theory for group actions on finite dimensional complexes EHT - Equivariant homotopy theory in context
Around 1940, P. A. Smith showed that if finite p-group P acts on a finite dimensional complex X that is acyclic in mod p homology, then the space of fixed points, XP, would also be acyclic in mod p homology. The more recent chromatic Smith theorem of Barthel et. al., says that if a finite abelian p-group A of rank r acts on a finite complex X that is acyclic in K(n+r) homology then XA will be acyclic in K(n) homology. (When stated this way, it has been implicitly assumed that XA is nonempty.) With William Balderrama, the speaker has given another proof of this theorem, in the spirit of standard proofs of Smith’s original theorem. The hypothesis that XA is nonempty is not needed: indeed this is proved enroute. Much of our proof works for all finite dimensional A-spaces X, not just finite ones, including proving the existence of a fixed point. This opens the question of whether the chromatic Smith theorem might also hold under this weaker hypothesis. Examples show that there is an obvious problem when n=0, but a nonequivariant theorem of Bousfield hints that this might be the only problem. In my talk, I will discuss our proof, and various open questions that it suggests.
EHT - Equivariant homotopy theory in context
- Speaker: Nicholas Kuhn (University of Virginia)
- Tuesday 27 May 2025, 14:00-15:00
- Venue: Seminar Room 2, Newton Institute.
- Series: Isaac Newton Institute Seminar Series; organiser: nobody.
Thu 01 May 17:00: Formalizing Fermat: an update
I have been “officially” formalizing Fermat’s Last Theorem for 6 months now, and unofficially I’ve been doing so for around a year. In this talk I’ll give you an update on where we are, how it’s going, and what I’ve learnt so far. More precisely, I’ll talk about infrastructure (what we’ve settled on, the problems that we’ve had, and how we solved them). I’ll talk about what the goals of the project are, what we have achieved, and where we’re going. And I’ll talk about what were (to me) some unexpected consequences of the formalization procedure, namely some old mathematics which we’ve poked holes in, and some new mathematics which has come out of the project. Finally I want to stress that I will not be assuming that the audience knows anything at all about the details of the proof! The talk will be suitable for a general scientific audience.
=== Hybrid talk ===
Join Zoom Meeting https://cam-ac-uk.zoom.us/j/87143365195?pwd=SELTNkOcfVrIE1IppYCsbooOVqenzI.1
Meeting ID: 871 4336 5195
Passcode: 541180
- Speaker: Kevin Buzzard (Imperial College London)
- Thursday 01 May 2025, 17:00-18:00
- Venue: MR14 Centre for Mathematical Sciences.
- Series: Formalisation of mathematics with interactive theorem provers ; organiser: Anand Rao Tadipatri.
Fri 09 May 16:00: Metastability Properties of the Earth's Climate: a Multiscale Viewpoint
The ultralow frequency variability of the Earth’s climate features an interplay of typically long periods of stasis accompanied by critical transitions between qualitatively different regimes associated with metastable states. Such transitions have often been accompanied by massive and rapid changes in the biosphere. Multiple transitions between the coexisting warm and snowball climates occurred more than 600 Mya and eventually led to conditions favourable to the development of multicellular life. The coexistence of such states is due to the instability associated with the positive ice-albedo feedback, Yet, this behaviour repeats itself across a wide range of timescales, spatial domains, and physical processes. Building on Hasselmann’s program, we propose here to interpret the time-evolution of the Earth system as a trajectory taking place in a dynamical landscape, whose multiscale features describe a hierarchy of metastable states and associated tipping points. We introduce the concept of climatic Melancholia states, saddle embedded in the boundary between the basins of attraction of the stable climates and explain under which conditions they act as gateways of noise-induced transitions. Using a hierarchy of numerical models, we discuss in detail the dichotomy between warm and snowball climate by bringing together the deterministic and stochastic viewpoint on the related global stability properties. We then discuss the paleoclimatically-relevant case where multiple competing climatic states are present and show the relevance of our angle for interpreting proxy data. Finally, if time allows, we will present some very recent results suggesting that our viewpoint might explain some intriguing aspects of the dynamical features of the tipping points of the Atlantic Meridional Overturning Circulation.
Key References V. Lucarini and T. Bodai, Transitions across Melancholia States in a Climate Model: Reconciling the Deterministic and Stochastic Points of View, Phys. Rev. Lett. 122, 158701 (2019) G. Margazoglou et al., Dynamical landscape and multistability of a climate model, Proc. R. Soc. A.477 210019 (2021) V. Lucarini, M.D. Chekroun, Theoretical tools for understanding the climate crisis from Hasselmann’s programme and beyond, Nature Reviews Physics 5 (12), 744-765 (2023) D. D. Rousseau et al., A punctuated equilibrium analysis of the climate evolution of cenozoic exhibits a hierarchy of abrupt transitions. Sci Rep 13, 11290 (2023) J. Lohmann et al., Multistability and Intermediate Tipping of the Atlantic Ocean Circulation, Sci. Advances 10 DOI : 10.1126/sciadv.adi4253 (2024)
- Speaker: Prof Valerio Lucarini, University of Leicester
- Friday 09 May 2025, 16:00-17:00
- Venue: MR2.
- Series: Fluid Mechanics (DAMTP); organiser: Professor Grae Worster.
Wed 30 Apr 14:00: Free Afternoon MHMW02 - Modern History of Mathematics: Looking Ahead
MHMW02 - Modern History of Mathematics: Looking Ahead
- Speaker:
- Wednesday 30 April 2025, 14:00-18:00
- Venue: No Room Required.
- Series: Isaac Newton Institute Seminar Series; organiser: nobody.
Thu 01 May 15:30: Between Mathematics, Logic, and Computing: Writing as the Material Culture of Theory MHMW02 - Modern History of Mathematics: Looking Ahead
In this talk I will present material from my current book project, Writing the Rules of Reason: The Social Life of Notation from Logic to Computing. It is a history of two fundamental transformations in the study of logic: First, logic was reconstructed from a humanistic study of reason to a mathematical science. Second, this new mathematical science was taken as a theoretical foundation for digital computing. I tell these intertwined stories by focusing on writing. How exactly does one write down an abstract logical statement? Before any theoretical construct could be embodied in a machine, it was first embodied on paper. Logicians always depended on inscriptive techniques to give physical form to their ideas, and different authors approached this problem in disparate ways. By centering notations and their communities of users, I show how the most abstract of sciences was rooted in the local milieus around an emerging transnational network of practitioners. Their work in logic was intertwined with local cultures and commitments. As notations proliferated, the growing diversity of symbolic techniques ultimately shaped not only the presentation but also the content of logic. My project builds on literature that has emphasized the importance of writing in the history of math, and calls for even great attention to the activities that record and perform theory on material surfaces. Focusing on writing grounds the history of math in histories of human practice.
MHMW02 - Modern History of Mathematics: Looking Ahead
- Speaker: David Dunning (Smithsonian Institution)
- Thursday 01 May 2025, 15:30-16:30
- Venue: Seminar Room 1, Newton Institute.
- Series: Isaac Newton Institute Seminar Series; organiser: nobody.
Fri 02 May 16:00: Connecting scales in the SMEFT at the LHC and future colliders
Given the absence of direct evidence for new resonances beyond the Standard Model at the LHC so far, a complementary strategy to search for new physics in an indirect way is provided by the Standard Model Effective Field Theory (SMEFT). Global interpretations within the SMEFT framework, including their matching to UV-complete models, involve energy scales spanning several orders of magnitude. In this talk, I will demonstrate how to relate these measurements among them in terms of a common energy scale as enabled by the Renormalisation Group Equations. I will then quantify their impact in a global SMEFT fit to LEP and LHC data, presenting results in terms of SMEFT parameters as well as UV couplings. Finally, I will show a brief application to the Higgs self-coupling using projected data from the HL-LHC and the FCC -ee.
- Speaker: Jaco ter Hoeve (University of Edinburgh)
- Friday 02 May 2025, 16:00-17:00
- Venue: MR19 (Potter Room, Pavilion B), CMS.
- Series: HEP phenomenology joint Cavendish-DAMTP seminar; organiser: Nico Gubernari.
Fri 13 Jun 10:15: Title TBC BPRW03 - Big proof: formalizing mathematics at scale
BPRW03 - Big proof: formalizing mathematics at scale
- Speaker: Wenda Li (University of Edinburgh)
- Friday 13 June 2025, 10:15-11:15
- Venue: Seminar Room 1, Newton Institute.
- Series: Isaac Newton Institute Seminar Series; organiser: nobody.
Tue 10 Jun 11:45: Title TBC BPRW03 - Big proof: formalizing mathematics at scale
BPRW03 - Big proof: formalizing mathematics at scale
- Speaker: Mario Carneiro (Chalmers University of Technology)
- Tuesday 10 June 2025, 11:45-12:45
- Venue: Seminar Room 1, Newton Institute.
- Series: Isaac Newton Institute Seminar Series; organiser: nobody.
Mon 12 May 15:30: Title Tbc EHTW03 - New horizons for equivariance in homotopy theory
EHTW03 - New horizons for equivariance in homotopy theory
- Speaker: Candace Bethea (Duke University)
- Monday 12 May 2025, 15:30-16:30
- Venue: Seminar Room 1, Newton Institute.
- Series: Isaac Newton Institute Seminar Series; organiser: nobody.
Thu 01 May 15:45: Maxime Wybouw EHT - Equivariant homotopy theory in context
EHT - Equivariant homotopy theory in context
- Speaker:
- Thursday 01 May 2025, 15:45-15:55
- Venue: Seminar Room 2, Newton Institute.
- Series: Isaac Newton Institute Seminar Series; organiser: nobody.
Thu 01 May 15:30: Yuqing Shi EHT - Equivariant homotopy theory in context
EHT - Equivariant homotopy theory in context
- Speaker:
- Thursday 01 May 2025, 15:30-15:40
- Venue: Seminar Room 2, Newton Institute.
- Series: Isaac Newton Institute Seminar Series; organiser: nobody.
Thu 01 May 15:15: David Chan EHT - Equivariant homotopy theory in context
EHT - Equivariant homotopy theory in context
- Speaker:
- Thursday 01 May 2025, 15:15-15:25
- Venue: Seminar Room 2, Newton Institute.
- Series: Isaac Newton Institute Seminar Series; organiser: nobody.
Thu 01 May 15:00: Tobias Barthel EHT - Equivariant homotopy theory in context
EHT - Equivariant homotopy theory in context
- Speaker:
- Thursday 01 May 2025, 15:00-15:10
- Venue: Seminar Room 2, Newton Institute.
- Series: Isaac Newton Institute Seminar Series; organiser: nobody.
Fri 09 May 14:00: Extrapolation-aware statistical machine learning
Nonparametric function estimation and prediction with moderate or large dimension of the covariates are particularly susceptible to extrapolation, because data points are typically far apart from each other in such moderate or higher dimension. Thus, there is a need to have machine learning methods that are extrapolation-aware, i.e. that automatically perform well (in a sense) when extrapolation occurs. Without such extrapolation-aware techniques, inference from standard machine learning and nonparametric procedures may be poor or invalid. We introduce a novel conceptual framework and introduce Xtrapolation which allows for extrapolation-aware inference with any ML algorithm.
This is joint work with Niklas Pfister (Lakera AI)
- Speaker: Peter Bühlmann (ETH Zurich)
- Friday 09 May 2025, 14:00-15:00
- Venue: MR12, Centre for Mathematical Sciences.
- Series: Statistics; organiser: Qingyuan Zhao.
Tue 27 May 14:00: Chromatic Smith theory for group actions on finite dimensional complexes EHT - Equivariant homotopy theory in context
Around 1940, P. A. Smith showed that if finite p-group P acts on a finite dimensional complex X that is acyclic in mod p homology, then the space of fixed points, XP, would also be acyclic in mod p homology. The more recent chromatic Smith theorem of Barthel et. al., says that if a finite abelian p-group A of rank r acts on a finite complex X that is acyclic in K(n+r) homology then XA will be acyclic in K(n) homology. (When stated this way, it has been implicitly assumed that XA is nonempty.) With William Balderrama, the speaker has given another proof of this theorem, in the spirit of standard proofs of Smith’s original theorem. The hypothesis that XA is nonempty is not needed: indeed this is proved enroute. Much of our proof works for all finite dimensional A-spaces X, not just finite ones, including proving the existence of a fixed point. This opens the question of whether the chromatic Smith theorem might also hold under this weaker hypothesis. Examples show that there is an obvious problem when n=0, but a nonequivariant theorem of Bousfield hints that this might be the only problem. In my talk, I will discuss our proof, and various open questions that it suggests.
EHT - Equivariant homotopy theory in context
- Speaker: Nikolas Kuhn (University of Oslo)
- Tuesday 27 May 2025, 14:00-15:00
- Venue: Seminar Room 2, Newton Institute.
- Series: Isaac Newton Institute Seminar Series; organiser: nobody.
Wed 21 May 14:00: Title to be confirmed
Abstract not available
- Speaker: Dr Bjarne Bergh, DAMTP, University of Cambridge
- Wednesday 21 May 2025, 14:00-15:00
- Venue: MR5, CMS Pavilion A.
- Series: Information Theory Seminar; organiser: Prof. Ramji Venkataramanan.
Fri 09 May 14:00: Title to be confirmed
Abstract not available
- Speaker: Peter Bühlmann (ETH Zurich)
- Friday 09 May 2025, 14:00-15:00
- Venue: MR12, Centre for Mathematical Sciences.
- Series: Statistics; organiser: Qingyuan Zhao.
Fri 02 May 14:00: Improved performance guarantees for Tukey’s median
Is there a natural way to order data in dimension greater than one? The approach based on the notion of half-space depth, often associated with the name of John Tukey, is among the most popular. Tukey’s depth has found applications in robust statistics, the study of elections and social choice, and graph theory. We will give an introduction to the topic, with an emphasis on robust statistics, describe some remaining open questions as well as our recent progress towards their solutions. In will particular, we discuss performance guarantees for Tukey’s median (and other affine-equivariant estimators) that depend on the “intrinsic” dimension of the problem expressed via the effective rank of the covariance matrix, and their connections to the size of empirical depth level sets.
This talk is based on the joint work with Yinan Shen.
- Speaker: Stanislav Minsker (University of Southern California)
- Friday 02 May 2025, 14:00-15:00
- Venue: MR12, Centre for Mathematical Sciences.
- Series: Statistics; organiser: Qingyuan Zhao.
Mon 28 Apr 14:00: Infalling charges and electromagnetic radiation
The Vlasov—Maxwell system describes the interaction of a large collection of collisionless charged particles. I will discuss a well posedness theorem for a ``scattering problem’’ for this system, in which the behaviour is prescribed in the infinite past. An arbitrarily prescribed configuration of particles fall in from infinity, with the condition of no incoming electromagnetic radiation imposed for the Maxwell field. The proof is based on our previous work on the Vlasov—Poisson system. I will then discuss properties of the radiation emitted by such a configuration. This is joint work with Volker Schlue (Melbourne).
- Speaker: Martin Taylor (Imperial)
- Monday 28 April 2025, 14:00-15:00
- Venue: MR13.
- Series: Partial Differential Equations seminar; organiser: Dr Greg Taujanskas.