Trajectory ML 01: From Observations to Hidden State

A shared framework for cell differentiation and character conversations, with a reproducible synthetic project and an honest distinction between geometry and time.

September 27, 2026 · 7 min · rick

Trajectory ML 09: Learn where a state moves next

Estimate a velocity field from paired observations, then discover why predicting one step and rolling out a trajectory are different tests.

September 27, 2026 · 6 min · rick

Trajectory ML 10: Move a population with optimal transport

Infer a mass-preserving coupling between snapshots, distinguish it from tracked identity, and implement Sinkhorn transport.

September 27, 2026 · 6 min · rick

Trajectory ML 11: Continuous dynamics and flow matching

Connect neural vector fields, ODEs, SDEs, and flow matching without confusing generated paths with observed temporal mechanisms.

September 27, 2026 · 6 min · rick

Trajectory ML 12: Outcomes, survival, and causal questions

Predict outcomes without future leakage, handle censored follow-up, and distinguish forecasting from the effect of an intervention.

September 27, 2026 · 2 min · rick

Trajectory ML: A Twelve-Lesson Course and Shared Lab

Recovering hidden states and trajectories from observations, from PCA to Flow Matching, survival analysis and causality, with one synthetic dataset.

September 27, 2026 · 7 min · rick

MacKay's Information Theory: The Free Book and the Lectures

David MacKay’s classic ties information theory, inference, and machine learning into one story, and both the book and the lecture videos are free. Where to get them, to open this series.

January 4, 2025 · 2 min · rick

K-means, GMM, EM: Three Nested Russian Dolls of Clustering

K-means is actually an extreme case of GMM, and GMM is the canonical application of the EM algorithm. How these three connect within a single framework, and how information geometry explains the relationship.

December 10, 2023 · 7 min · rick

Information Geometry: How AI Learns Most Efficiently

Just as Newton’s F=ma describes the physical world, information geometry describes how AI learns. An intuitive guide for beginners.

January 9, 2021 · 4 min · rick