|Talks|

Probabilistic hyperbolic embedding of networks

Visiting speaker
Hybrid
Past Talk
Simon Lizotte
Ph.D. Candidate / Université Laval
Wed, Apr 30, 2025
3:00 PM UTC
Wed, Apr 30, 2025
3:00 PM UTC
In-person
4 Thomas More St
London E1W 1YW, UK
The Roux Institute
Room
100 Fore Street
Portland, ME 04101
Network Science Institute
2nd floor
Network Science Institute
11th floor
177 Huntington Ave
Boston, MA 02115
Network Science Institute
2nd floor
Room
58 St Katharine's Way
London E1W 1LP, UK

Talk recording

Hyperbolic space provides a natural latent geometry for complex networks, as random geometric graphs constructed in this space reproduce many empirical network properties. The inverse problem—recovering the hyperbolic coordinates that best represent a given graph—enables efficient network routing and has been used for link prediction. Although this is a challenging optimization task due to the abundance of local maxima, many performant algorithms have been developed. However, these methods ignore uncertainty in the embeddings, producing a single solution without quantifying error or acknowledging alternative configurations. The first part of this talk introduces the principles of hyperbolic geometry and Bayesian inference, two disciplines rarely combined. The second part of the talk discusses BIGUE, a Markov chain Monte Carlo algorithm that samples from the posterior of a Bayesian model for hyperbolic random graphs. BIGUE leverages the space symmetries to achieve better mixing than both random walk and a Hamiltonian Monte Carlo methods. The resulting credible intervals align with existing embedding methods, while also revealing the potential for multimodal posteriors, which we demonstrate using a synthetic graph model.
About the speaker
Simon is a Ph.D. student in Physics at Dynamica at Université Laval, advised by Antoine Allard and coadvised by Jean-Gabriel Young. He obtained his Master’s degree also at Dynamica in 2022 under the supervision of Antoine Allard and Jean-Gabriel Young. He is interested in the intricacies of the structure of complex networks. He uses Bayesian statistics and computational methods to improve our understanding of network models and properties.
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Apr 30, 2025