Scalable Simulation-free Entropic Unbalanced Optimal Transport
Jaemoo Choi, Jaewoong Choi

TL;DR
This paper introduces a scalable, simulation-free method for solving the Entropic Unbalanced Optimal Transport problem, enhancing efficiency in generative modeling and image translation tasks.
Contribution
It derives a dynamical form and dual formulation of EUOT, and proposes SF-EUOT, a simulation-free algorithm that improves scalability over existing Schr"odinger bridge methods.
Findings
Achieves simulation-free training and generation.
Significantly improves scalability in generative tasks.
Reduces computational costs compared to previous SB methods.
Abstract
The Optimal Transport (OT) problem investigates a transport map that connects two distributions while minimizing a given cost function. Finding such a transport map has diverse applications in machine learning, such as generative modeling and image-to-image translation. In this paper, we introduce a scalable and simulation-free approach for solving the Entropic Unbalanced Optimal Transport (EUOT) problem. We derive the dynamical form of this EUOT problem, which is a generalization of the Schr\"odinger bridges (SB) problem. Based on this, we derive dual formulation and optimality conditions of the EUOT problem from the stochastic optimal control interpretation. By leveraging these properties, we propose a simulation-free algorithm to solve EUOT, called Simulation-free EUOT (SF-EUOT). While existing SB models require expensive simulation costs during training and evaluation, our model…
Peer Reviews
Decision·Submitted to ICLR 2025
1) The novel dual formulation of Entropic Unbalanced Optimal Transport based on the connections between Entropic Optimal Transport, Schrödinger Bridge, and Action Matching seems promising in unifying the mentioned problems. 2) The obtained experimental results support the author's claim that the new simulation-free solver outperforms the previous approach for SB/Entropic Optimal Transport. 3) The results for image generations presented for CIFAR-10 are comparable with the diffusion/flow models
1) While the general theory is clear and strict, some questions arise about the claims in sections 4.1 and 4.2 regarding the description and justification of the proposed method (see questions).
1. The work demonstrates novelty as the first EOT model that does not require pretraining. Based on the known equivalence between Schrödinger Bridge (SB) and EOT, the authors introduced EUOT by fixing the source distribution and proved that it generalizes EOT (and thus SB). 2. Thanks to its reciprocal property and static generator, EUOT is a simulation-free model that does not require SDE or ODE simulations for sampling.
1. Theoretically, compared to EOT, EUOT only adds an $f$-divergence penalty term in the objective to relax the marginal constraint, which doesn’t seem like a groundbreaking innovation. 2. While the results surpass other OT methods, EUOT does not achieve the best FID scores compared to other image generation models (Tab. 1). Additionally, Fig. 3 indicates that EUOT does not fully approximate a precise optimal transport plan, and Tab. 3 shows that EUOT performs slightly worse than some benchmarks
The paper is overall well written. It introduces a well motivated method by deriving a suitable dual dynamic formulation of the EUOT problem, and rewriting it as a stochastic optimal control problem. The experiments on generative modeling seem good.
On the presentation of the paper, I believe some things could be improved. For instance, in Section 4.1, a lot of equations are presented, which are obtained by performing only some rewriting (e.g. equation (21) to (22) and then (22) to (24)). While this is very clear, I would suggest to just report the last equation (24) with some description of what has been done, and report the detailed derivations in Appendix. Also, the legend of Figure 3 are too small. A lot of abreviations are not given or
Videos
No videos yet. Explain this paper in a talk, walkthrough, or lecture? Add one.
Taxonomy
TopicsAdvanced Queuing Theory Analysis · Transportation Planning and Optimization · Traffic control and management
