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OT-net: a reusable neural optimal transport solver

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Abstract

With the widespread application of optimal transport (OT), its calculation becomes essential, and various algorithms have emerged. However, the existing methods either have low efficiency or cannot represent discontinuous maps. A novel reusable neural OT solver OT-Net is thus presented, which first learns Brenier’s height representation via the neural network to get its potential, and then obtains the OT map by the gradient of the potential. The algorithm has two merits: (1) When new target samples are added, the OT map can be calculated straightly, which greatly improves the efficiency and reusability of the map. (2) It can easily represent discontinuous maps, which allows it to match any target distribution with discontinuous supports and achieve sharp boundaries, and thus eliminate mode collapse. Moreover, we conducted error analyses on the proposed algorithm and demonstrated the empirical success of our approach in image generation, color transfer, and domain adaptation.

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Availability of data and material

The data/reanalysis that supports the findings of this study are publicly available online at http://yann.lecun.com/exdb/mnist/, and https://github.com/zalandoresearch/fashion-mnist, and http://www.cs.toronto.edu/kriz/cifar.html, and http://mmlab.ie.cuhk.edu.hk/projects/CelebA.html.

Code availability

The code can be obtained by contacting Shenghao Li and Zezeng Li.

Notes

  1. https://pythonot.github.io/#

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Funding

This research was supported by the National Key R &D Program of China (2021YFA1003003), and the National Natural Science Foundation of China under Grant (61936002, T2225012).

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Contributions

ZL provided original ideas and code implementation of the proposed algorithm. SL was responsible for most of the experimental validation and manuscript writing. LJ, NL, and ZL provided constructive ideas for theoretical derivation and experimental setup. All authors participated in the writing of the manuscript, and read and approved the final manuscript.

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Correspondence to Na Lei.

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Editor: Hendrik Blockeel.

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Appendix A

Appendix A

This section introduces the Encoder–Decoder architecture that is applied to the generative model and height representation network architecture of our algorithm. The autoencoder network structures are presented in Tables 7 and 8, and the height representation network structure can be found in Table 9, where \(P_{data}\) and \(P_{latent}\) represent the data distribution and the latent coding distribution, respectively. The Encoder–Decoder architecture was trained using the Adam algorithm with mini-batches of size 512, and learning rates of 2e-4, 1e-4, and 2e-5 in FASHION-MNIST Xiao et al. (2017), Cifar-10 Krizhevsky et al. (2009), and CelebA Zhang et al. (2018), respectively. The height representation network was also trained using Adam with mini-batches of size 512, and learning rates of 0.004, 0.005, and 0.005 in FASHION-MNIST, Cifar-10, and CelebA, respectively.

Table 7 The Encoder architecture for CelebA, FASHION-MNIST and Cifar-10
Table 8 The Decoder architecture for CelebA, FASHION-MNIST and Cifar-10
Table 9 The height representation architecture for OT-Net

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Li, Z., Li, S., Jin, L. et al. OT-net: a reusable neural optimal transport solver. Mach Learn 113, 1243–1268 (2024). https://doi.org/10.1007/s10994-023-06493-9

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