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Matthias Heymann coauthored the geometric minimum action with Eric Vanden-Eijnden. Their algorithm minimizes a geometric form of the Freidlin--Wentzell action to calculate rare transition paths and the quasipotential. Examples include a bistable stochastic differential equation and a genetic-switch Markov jump process, showing how one variational principle applies to different stochastic models.^[ref]

By Matthias Heymann, Eric Vanden-Eijnden.

Communications on Pure and Applied Mathematics 61, 1052–1117. DOI: doi.org/10.1002/cpa.20238 . Author-hosted PDF. Sections 1.1–1.3: action admissibility, noise convention, free-time quasipotential and geometric reformulation. Wiki uses drift a and covariance D to avoid the paper's a/b notation ambiguity; the time-reparameterization and gradient examples are explicitly derived.