Thu, 04 Jun 2026
11:00
C3

Avoiding logical strength in analysis

Anton Freund
(Universität Würzburg)
Abstract
In reverse mathematics, one classically represents real numbers by Cauchy sequences (q_n) with a known rate of convergence, where typically |q_m-q_n|<2^{-m} for m<n. While this has good reasons, it turns out that "slow" Cauchy sequences (without prescribed rate of convergence) have great advantages as well: In joint work with Nicholas Pischke and Patrick Uftring (arXiv:2605.15151), we have shown that almost all one-dimensional real analysis from the textbook by Simpson can be developed in theories that are Pi^1_1-conservative over RCA_0 (including results that require ACA_0 with the classical representation). This yields a very different picture of the foundations of analysis, which also blurs the boundary between analytical principles and combinatorial principles from the so-called reverse mathematics zoo.
Exploring the relationship between vascular remodelling and tumour growth using agent-based modelling.
Fan, N Bull, J Byrne, H PLoS computational biology volume 22 issue 5 e1012967 (15 May 2026)
Tensorial permanence of K‐stability for diagonal AH‐algebras
Seth, A Bulletin of the London Mathematical Society volume 58 issue 5 (22 May 2026)

Steering the Disruption: AI's Transformation of Science and the Role of Philanthropy - Dr Stuart Feldman (President and Chief Scientist of Schmidt Sciences)

Sheldonian Theatre, 17 June, 5.30 p.m.

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Out-group comparison of free-living bird nest inhabiting astigmatan mite chelae
Bowman, C Biologia - Section Zoology
Interpretable machine learning and signal processing for automated reading and quality control of lateral flow tests for schistosomiasis
Ho, C Puthur, C Nabatte, B Moore, C Abdoel, T Paulussen, R Nganjimi, P Hoekstra, P Kabatereine, N Kawesa, B Odea, J Bogere, R Katushabe, R van Dam, G Scherr, T Chami, G Nature Communications (18 May 2026)
A Bayesian modelling framework for inference of latent infection risk patterns from virus neutralisation assay titration data
Alrefae, T Pons-Salort, M Donnelly, C Lambert, B Kamau, E (21 May 2026)
Particle Systems and McKean--Vlasov Dynamics with Singular Interaction through Local Times
Hambly, B Jettkant, P Baker, G Annals of Probability
Wed, 27 May 2026
12:00
L6, Mathematical Institute

Sumsets of sets of positive density in the integers

Ethan Ackelsberg
Abstract
A central object of study in additive combinatorics is the sumset A+B of two sets A and B. Two of the basic questions one may ask are direct questions (“how large must A+B be in terms of the sizes of A and B?”) and inverse questions (“if A+B is small, what can be deduced about the structure of A and B?”). When A and B are infinite subsets of the integers with size quantified by natural density d(·), Kneser (1953) proved the direct theorem that d(A+B) ≥ d(A) + d(B) unless A and B have certain modular obstructions. Erdős and Graham (1980) asked for a corresponding inverse theorem classifying sets with d(A+B) = d(A) + d(B). In this talk, we will present a new result characterizing the pairs of sets satisfying d(A+B) = d(A) + d(B) in the absence of modular obstructions. This talk is based on joint work with Florian K. Richter.


 

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