This session is aimed at first-year undergraduates preparing for Prelims exams. A panel of lecturers and current students will share key advice on exam technique and revision strategies, offering practical tips from their own experience.
This week’s Fridays@2 session is intended to provide advice on exam preparation and how to approach the Part A, B, and C exams. A panel consisting of past examiners and current students will answer any questions you might have as you approach exam season.
Join us for a lively one-day event bringing together researchers, professional staff, community partners, and anyone interested in public and community engagement with research. The conference is open to University of Oxford members, as well as the wider public, including community organisations and colleagues from other universities.
Thursday 11 June 2026, 9 am to 6 pm, Life and Mind Building, Oxford
Dovetail Research are currently recruiting for a paid 10-week research fellowship (full-time or part-time). They have recently received funding from ARIA to carry out theoretical research in AI safety, and are seeking applicants with strong mathematical research ability, regardless of prior experience in AI safety. Further details
Image: Gustave Courbet: The Grain Sifters
Registrations are now open for the annual MPLS Mental Health Awareness Week (11-17 May 2026) programme.
Start Trinity term with a spring in your step. Staff and students are invited to join a series of biodiversity walks through University Parks and Park Farm. Learn about trees, bees, and local conservation work, while contributing to citizen science initiatives, guided by our very own specialists. Starting on 27 April.
Participation is free, but registration is essential.
Professor Amir Ali Ahmadi will talk about; 'Disjunctive Sum of Squares'
We introduce the concept of disjunctive sum of squares for certifying nonnegativity of polynomials. Unlike the popular sum of squares approach, where nonnegativity is certified by a single algebraic identity, the disjunctive sum of squares approach certifies nonnegativity using multiple algebraic identities. Our main result is a disjunctive Positivstellensatz showing that the degree of each algebraic identity can be kept as low as the degree of the polynomial whose nonnegativity is in question. Based on this result, we construct a semidefinite programming–based converging hierarchy of lower bounds for the problem of minimizing a polynomial over a compact basic semialgebraic set, in which the size of the largest semidefinite constraint remains fixed throughout the hierarchy. We further prove a second disjunctive Positivstellensatz, which leads to an optimization-free hierarchy for polynomial optimization. We specialize this result to the problem of proving copositivity of matrices. Finally, we describe how the disjunctive sum of squares approach can be combined with a branch-and-bound algorithm, and we present numerical experiments on polynomial, copositive, and combinatorial optimization problems. The talk is self-contained and assumes no prior background in sum of squares optimization.
Amir Ali Ahmadi is a Professor of Operations Research and Financial Engineering at Princeton University, with affiliated appointments across applied mathematics, computer science, engineering, statistics, robotics, and AI. He directs Princeton’s Minor in Optimization and Quantitative Decision Science and has also held visiting research roles at Citadel and Google Brain. He earned his PhD in EECS from MIT and was a Goldstine Fellow at IBM Research before joining Princeton. His research focuses on optimization, dynamical systems, control-oriented learning, and algorithmic complexity. He has received numerous honors, including the Sloan Fellowship, PECASE, NSF CAREER Award, DARPA Faculty Award, and several major prizes in optimization and control. He is also widely recognized for his teaching and research, with multiple best-paper awards and major teaching awards at Princeton and beyond. You can read his full bio here.