# ★ Simulation-Based Homotopy: Stress-Testing Gravitational-Wave Posteriors ★ - Institution: CERN - Speaker: Giada Chiara Badaracco - Year: 2026 - Language: English - Source: [CERN](https://videos.cern.ch/record/3025585) - Licence: [CERN](https://copyright.web.cern) - Who can watch: Teens profiles and older (sources give no ratings; placed by Invisible Network from the source's own words) We present a framework for probing the full geometry of Bayesian posteriors in inverse problems through a noise-conditioned homotopy. By embedding the likelihood in a one-parameter family controlled by a noise-scaling parameter, we construct a continuous deformation from an almost deterministic posterior concentrated at the true parameters to the full noisy posterior. Traversing this path reveals how posterior structure evolves with measurement quality: when multi-modality emerges, where Gaussian approximations break down, and how parameter degeneracies develop. We argue this constitutes a more integrated alternative to Fisher-information analyses, which becomes beneficial especially in multimodal geometries. Additionally, deviations from smooth homotopy behaviour provide direct diagnostics of inference pipelines, allowing identification of spurious correlations, mode-collapse artefacts, and approximation breakdowns. We discuss the framework as a general validation and benchmarking tool for simulation-based inference methods. 00:00:00 Slide 1 00:00:28 Slide 2 00:00:49 Slide 3 00:01:13 Slide 4 00:01:46 Slide 5 00:02:18 Slide 6 00:03:39 Slide 7 00:04:50 Slide 8 00:06:24 Slide 9 00:07:02 Slide 10 00:07:48 Slide 11 00:08:54 Slide 12 00:10:57 Slide 13 00:12:43 Slide 14 00:13:47 Slide 15 00:14:22 Slide 16 00:16:27 Slide 17 00:17:16 Slide 18 00:17:51 Slide 19 00:18:12 Slide 20 00:18:40 Slide 21 00:19:01 Slide 22 00:20:58 Slide 23 00:21:43 Slide 24 ## Lectures 1. [★ Simulation-Based Homotopy: Stress-Testing Gravitational-Wave Posteriors ★](https://invisiblenetwork.ai/learn/cern/3025585/d3036c3919b4), 23 min (CERN's player)