Compressors

Defining a Belief Compressor

In this section, we outline the requirements and guidelines for defining a belief Compressor.

Interface

The Compressor interface is extremely minimal. It only supports two methods: fit! and the associated functor. For example, if you wanted to implement your own Compressor, you could write something like this

struct MyCompressor <: Compressor
    foo
    bar
end

# functor definition
function (c::MyCompressor)(beliefs)
    # YOUR CODE HERE
    return compressed_beliefs
end

function fit!(c::MyCompressor, beliefs)
    # YOUR CODE HERE
end

Implementation Tips

• For robustness, both the functor and fit! should be able to handle AbstractVector and AbstractMatrix inputs.
• fit! is called only once after beliefs are sampled from the POMDP.
• CompressedBeliefSolver will attempt to convert each belief state (often of type DiscreteBelief) into an AbstractArray{Float64} using convert_s. As a convenience, CompressedBeliefMDP implements conversions for commonly used belief types; however, if the POMDP has a custom belief state, then it is the users' responsibility to implement the appropriate conversion. See the source code for help.

Implemented Compressors

CompressedBeliefMDPs currently provides wrappers for the following compression types:

• a principal component analysis (PCA) compressor,
• a kernel PCA compressor,
• a probabilistic PCA compressor,
• a factor analysis compressor,
• an isomap compressor,
• an autoencoder compressor
• a variational auto-encoder (VAE) compressor

Principal Component Analysis (PCA)

Kernel PCA

Probabilistic PCA

Factor Analysis

Isomap

Autoencoder

Variational Auto-Encoder (VAE)