Computational Biology
Three-panel diagram showing input point sets, SVD factorization of the cross-covariance matrix, and the aligned result

Arun et al.: SVD-Based Least-Squares Fitting of 3D Points

Presents a concise SVD-based algorithm for finding the optimal rotation and translation between two 3D point sets, with analysis of the degenerate reflection case that Umeyama later corrected.

Computational Biology
Diagram showing the polar decomposition of the cross-covariance matrix M into orthonormal factor U and positive semidefinite square root

Horn et al.: Absolute Orientation Using Orthonormal Matrices

The matrix-based companion to Horn’s 1987 quaternion method, deriving the optimal rotation as the orthonormal factor in the polar decomposition of the cross-covariance matrix via eigendecomposition of a 3x3 symmetric matrix.

Computational Biology
Side-by-side comparison showing naive SVD producing a reflected alignment versus Umeyama's corrected proper rotation

Umeyama's Method: Corrected SVD for Point Alignment

Corrects a flaw in prior SVD-based alignment methods (Arun et al., Horn et al.) that could produce reflections instead of rotations under noisy data, and provides a complete closed-form solution for similarity transformations in arbitrary dimensions.

Generative Modeling
Diagram showing consistency models mapping points on a PF ODE trajectory to the same origin

Consistency Models: Fast One-Step Diffusion Generation

This paper introduces consistency models, a new family of generative models that map any point on a Probability Flow ODE trajectory to its origin. They support fast one-step generation by design, while allowing multi-step sampling for improved quality and zero-shot editing tasks like inpainting and colorization.

Computational Biology
3D scatter plot showing left and right point sets with rotation axis and quaternion rotation arc

Horn's Method: Absolute Orientation via Unit Quaternions

Derives the optimal rotation between two 3D point sets as the eigenvector of a 4x4 symmetric matrix built from cross-covariance sums, using unit quaternions to enforce the orthogonality constraint.

Computational Biology
3D scatter plot showing source points, target points, and Kabsch-aligned points overlapping the targets

Kabsch Algorithm: Optimal Rotation for Point Set Alignment

A foundational 1976 short communication presenting a direct, non-iterative method for finding the best rotation matrix between two point sets via eigendecomposition of a cross-covariance matrix.

Machine Learning Fundamentals
Comparison of linear interpolation (teleportation) showing double peaks versus displacement interpolation (transportation) showing smooth single peak

A Convexity Principle for Interacting Gases (McCann 1997)

A theoretical paper that introduces displacement interpolation (optimal transport) to establish a new convexity principle for energy functionals. It proves the uniqueness of ground states for interacting gases and generalizes the Brunn-Minkowski inequality, providing mathematical tools later used in flow matching and optimal transport-based generative models.

Generative Modeling
Visualization of probability density flow from initial distribution ρ₀ to target distribution ρ₁ over time through space

Building Normalizing Flows with Stochastic Interpolants

Proposes ‘InterFlow’, a method to learn continuous normalizing flows between arbitrary densities using stochastic interpolants. It avoids ODE backpropagation by minimizing a quadratic objective on the velocity field, enabling scalable ODE-based generation. On CIFAR-10, NLL matches ScoreSDE (2.99 bits per dim) with simulation-free training, though FID (10.27) trails dedicated image models (ScoreSDE: 2.92); the primary strength is tractable likelihood with efficient training cost.

Generative Modeling
Visualization comparing Optimal Transport (straight paths) vs Diffusion (curved paths) for Flow Matching

Flow Matching for Generative Modeling: Scalable CNFs

Introduces Flow Matching, a scalable method for training CNFs by regressing vector fields of conditional probability paths. It generalizes diffusion and enables Optimal Transport paths for straighter, more efficient sampling.

Machine Learning Fundamentals
Comparison of Residual Network vs ODE Network architectures showing discrete layers versus continuous transformations

Neural ODEs: Continuous-Depth Deep Learning Models

This paper replaces discrete network layers with continuous ordinary differential equations (ODEs), allowing for adaptive computation depth and constant memory cost during training via the adjoint sensitivity method. It introduces Continuous Normalizing Flows and latent ODEs for time-series.

Generative Modeling
Visualization showing linear interpolation, learned ODE trajectories, and the reflow straightening process for rectified flow

Rectified Flow: Learning to Generate and Transfer Data

Introduces ‘Rectified Flow,’ a method to transport distributions via ODEs with straight paths. Uses a ‘reflow’ procedure to iteratively straighten trajectories, enabling high-quality 1-step generation with optional lightweight distillation.

Generative Modeling
Denoising Score Matching Intuition - Vectors point from corrupted samples back to clean data, approximating the score

Score Matching and Denoising Autoencoders: A Connection

This paper provides a rigorous probabilistic foundation for Denoising Autoencoders by proving they are mathematically equivalent to Score Matching on a kernel-smoothed data distribution. It derives a specific energy function for DAEs and justifies the use of tied weights.