This paper introduces a novel type theory and logic for probabilistic reasoning. Its logic is quantitative, with fuzzy predicates. It includes normalisation and conditioning of states. This conditioning uses a key aspect that distinguishes our probabilistic type theory from quantum type theory, namely the bijective correspondence between predicates and side-effect free actions (called instrument, or assert, maps). The paper shows how suitable computation rules can be derived from this predicate-action correspondence, and uses these rules for calculating conditional probabilities in two well-known examples of Bayesian reasoning in (graphical) models. Our type theory may thus form the basis for a mechanisation of Bayesian inference.
@InProceedings{adams_et_al:LIPIcs.TYPES.2015.1, author = {Adams, Robin and Jacobs, Bart}, title = {{A Type Theory for Probabilistic and Bayesian Reasoning}}, booktitle = {21st International Conference on Types for Proofs and Programs (TYPES 2015)}, pages = {1:1--1:34}, series = {Leibniz International Proceedings in Informatics (LIPIcs)}, ISBN = {978-3-95977-030-9}, ISSN = {1868-8969}, year = {2018}, volume = {69}, editor = {Uustalu, Tarmo}, publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik}, address = {Dagstuhl, Germany}, URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.TYPES.2015.1}, URN = {urn:nbn:de:0030-drops-84714}, doi = {10.4230/LIPIcs.TYPES.2015.1}, annote = {Keywords: Probabilistic programming, probabilistic algorithm, type theory, effect module, Bayesian reasoning} }
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