Variational Inference with NoFAS: Normalizing Flow with Adaptive
Surrogate for Computationally Expensive Models
- URL: http://arxiv.org/abs/2108.12657v1
- Date: Sat, 28 Aug 2021 14:31:45 GMT
- Title: Variational Inference with NoFAS: Normalizing Flow with Adaptive
Surrogate for Computationally Expensive Models
- Authors: Yu Wang, Fang Liu and Daniele E. Schiavazzi
- Abstract summary: Use of sampling-based approaches such as Markov chain Monte Carlo may become intractable when each likelihood evaluation is computationally expensive.
New approaches combining variational inference with normalizing flow are characterized by a computational cost that grows only linearly with the dimensionality of the latent variable space.
We propose Normalizing Flow with Adaptive Surrogate (NoFAS), an optimization strategy that alternatively updates the normalizing flow parameters and the weights of a neural network surrogate model.
- Score: 7.217783736464403
- License: http://creativecommons.org/licenses/by-nc-nd/4.0/
- Abstract: Fast inference of numerical model parameters from data is an important
prerequisite to generate predictive models for a wide range of applications.
Use of sampling-based approaches such as Markov chain Monte Carlo may become
intractable when each likelihood evaluation is computationally expensive. New
approaches combining variational inference with normalizing flow are
characterized by a computational cost that grows only linearly with the
dimensionality of the latent variable space, and rely on gradient-based
optimization instead of sampling, providing a more efficient approach for
Bayesian inference about the model parameters. Moreover, the cost of frequently
evaluating an expensive likelihood can be mitigated by replacing the true model
with an offline trained surrogate model, such as neural networks. However, this
approach might generate significant bias when the surrogate is insufficiently
accurate around the posterior modes. To reduce the computational cost without
sacrificing inferential accuracy, we propose Normalizing Flow with Adaptive
Surrogate (NoFAS), an optimization strategy that alternatively updates the
normalizing flow parameters and the weights of a neural network surrogate
model. We also propose an efficient sample weighting scheme for surrogate model
training that ensures some global accuracy of the surrogate while capturing the
likely regions of the parameters that yield the observed data. We demonstrate
the inferential and computational superiority of NoFAS against various
benchmarks, including cases where the underlying model lacks identifiability.
The source code and numerical experiments used for this study are available at
https://github.com/cedricwangyu/NoFAS.
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