added more documentation

docs/make.jl

@@ -14,7 +14,10 @@ makedocs(
     modules = [CompressedBeliefMDPs],
     pages = [
         "CompressedBeliefMDPs.jl" => "index.md",
+        "Concepts and Architecture" => "concepts.md",
+        "Defining a Sampler" => "sampler_interface.md",
         "Implemented Samplers" => "samplers.md",
+        "Defining a Compressor" => "compressor_interface.md",
         "Implemented Compressors" => "compressors.md",
         "API Documentation" => "api.md"
         # "Subsection" => [

docs/src/compressor_interface.md

@@ -0,0 +1,28 @@
+# 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](https://docs.julialang.org/en/v1/manual/methods/#Function-like-objects). For example, if you wanted to implement your own `Compressor`, you could write something like this
+
+```julia
+struct MyCompressor <: Compressor
+    foo
+    bar
+end
+
+# functor definition
+function (c::MyCompressor)(beliefs)
+    # YOUR CODE HERE
+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`](https://juliapomdp.github.io/POMDPs.jl/latest/POMDPTools/beliefs/#POMDPTools.BeliefUpdaters.DiscreteBelief)) into an `AbstractArray{Float64}` using [`convert_s`](https://juliapomdp.github.io/POMDPs.jl/latest/api/#POMDPs.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. 

docs/src/concepts.md

@@ -0,0 +1,11 @@
+# Concepts and Architecture
+
+CompressedBeliefMDPs.jl aims to implement a generalization of the [belief compression algorithm](https://papers.nips.cc/paper_files/paper/2002/hash/a11f9e533f28593768ebf87075ab34f2-Abstract.html) for solving large POMDPs. The algorithm has four steps:
+1. collect belief samples,
+2. compress the samples,
+3. create the compressed belief-state MDP,
+4. solve the MDP.
+
+Each step is handled by `Sampler`, `Compressor`, `CompressedBeliefMDP`, and `CompressedBeliefSolver` respectively.
+
+For more details, please see the rest of the documentation or the [associated paper](../../paper.md).

docs/src/sampler_interface.md

@@ -0,0 +1,20 @@
+# Defining a Sampler
+
+In this section, we outline the requirements and guidelines for defining a belief `Sampler`.
+
+## Interface
+
+The `Sampler` interface only has one method: the [functor](https://docs.julialang.org/en/v1/manual/methods/#Function-like-objects). For example, if you wanted to implement your own `Sampler`, you could write something like this
+
+```julia
+struct MySampler <: Compressor
+    foo
+    bar
+end
+
+# functor definition
+function (c::MySampler)(pomdp::POMDP)
+    # YOUR CODE HERE
+end
+```
+