# Compositionality in algorithms for smoothing

arXiv: https://arxiv.org/abs/2303.13865 · HTML: https://mlsanity.com/paper/2303.13865/

## Key facts

- Cited by 1 papers in the map (data through 14 Oct 2026).
- First posted on arXiv 24 Mar 2023.

## Built on by (most cited first, 1 of 1)

- [String Diagrams with Factorized Densities](https://mlsanity.com/paper/2305.02506/) (2023)

## Abstract (arXiv)

Backward Filtering Forward Guiding (BFFG) is a bidirectional algorithm proposed in Mider et al. [2021] and studied more in depth in a general setting in Van der Meulen and Schauer [2022]. In category theory, optics have been proposed for modelling systems with bidirectional data flow. We connect BFFG with optics by demonstrating that the forward and backwards map together define a functor from a category of Markov kernels into a category of optics, which is furthermore lax monoidal in the case when the guiding kernels coincide with the generative dynamics