The PhD defence will be in Abels utsikt - Niels Henrik Abels hus. The host of the session will moderate the technicalities while the chair of the defence will moderate the disputation.
Join Zoom Meeting
https://uio.zoom.us/j/66588673922
Meeting ID: 665 8867 3922
Ex auditorio questions: the chair of the defence will invite the audience to ask questions ex auditorio at the end of the defence.
Trial lecture
November 28th, time: 10:15 am, room 1259 (Abels utsikt).
Martingale posteriors in modern AI
Main research findings
Modern digital services such as online marketplaces, streaming services and large language models rely on algorithms that predict the user's needs and wishes. These systems are often based on powerful neural networks trained on large volumes of data. However, models often struggle when data are limited or biased, or when exposed to new situations that differ from their training. In such cases, models may be overconfident and make poor predictions.
This thesis explores how Bayesian neural networks can make such systems both more reliable and flexible. Bayesian models not only provide calibrated uncertainty estimates but also allow information to be shared hierarchically across related tasks and datasets. In large-scale recommender systems, I show how uncertainty can guide better exploration, improve diversity, and enable more realistic evaluation using impression-aware datasets that include both shown and clicked items. For large language models, I develop BoRA, a Bayesian hierarchical extension of LoRA, which lets multiple tasks borrow strength from a shared prior while still adapting independently when data are sufficient. Together, these results demonstrate that Bayesian reasoning can make AI systems more data-efficient, transparent, and reliable at scale.
Candidate contact information
LinkedIn: https://www.linkedin.com/in/simeneide/
Adjudication committee
Tenure-track research group leader at Helmholtz AI, Vincent Fortuin, University of Munich
Associate Professor Özlem Özgöbek, NTNU
Associate Professor Emil Stoltenberg, University of Oslo
Supervisors
Associate Professor Riccado de Bin, University of Oslo
Professor Arnoldi Frigessi, University of Oslo
Professor David Leslie, Lancaster University
Chair of defence
Head of Department Geir Dahl
Host of the session
Associate Professor Emil Stoltenberg, University of Oslo