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Approximate distribution

As explained in Bayesian Optimization in Action

A variational distribution is an optimized probability distribution that approximates an intractable posterior distribution in variational inference.

A variational distribution defines a probability distribution over a VGP’s inducing points. Optimization adjusts it so the variational model resembles a GP trained on the full dataset. section 12.2.3

In a GPyTorch variational Gaussian process, the distribution:

  • Uses CholeskyVariationalDistribution, initialized with the number of inducing points. section 12.2.3
  • Works with a variational strategy that updates the distribution and produces predictions from inducing points. section 12.2.3
  • Is optimized with the VGP’s ELBO during mini-batch gradient descent. section 12.2.3

VGP construction

Create the distribution with the number of inducing points, pass it to VariationalStrategy with learn_inducing_locations=True, and train the resulting model with VariationalELBO. section 12.2.3

Table 12.3 Necessary components when implementing a GP vs. a VGP in GPyTorch. A VGP requires a mean and covariance module like a GP but additionally needs a variational distribution and a variational strategy. (view table figure)

Components

GP

VGP

Mean module

Yes

Yes

Covariance module

Yes

Yes

Variational distribution

No

Yes

Variational strategy

No

Yes

Compare the components required by a standard GP and a VGP: the VGP adds a variational distribution and variational strategy. section 12.2.3

How Bayesian Optimization in Action covers it

How deep it goes
Defines implementation components and training roles, but stops short of deriving the variational distribution mathematically.
Examples
Uses CholeskyVariationalDistribution, VariationalStrategy, inducing-point learning, mini-batch training, and GP–VGP prediction comparisons.
What you can do after
Apply it via GPyTorch by constructing a variational distribution, connecting a strategy, and optimizing the ELBO.
How it connects
Connects inducing points, variational strategies, Gaussian processes, VGPs, and ELBO optimization.

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This explainer was generated by Manning's knowledge graph from the text of Bayesian Optimization in Action. The section links point to the parts of the book it draws on.