,
Tomer Samara
Creative Commons Attribution 4.0 International license
A standard intensional account of probabilistic computation represents a randomized program as a deterministic computation that consumes an explicit random tape. This yields a two-layer perspective: an intensional layer that makes reuse of randomness and correlation visible, and an extensional layer obtained by interpreting tapes under a chosen probability measure. We develop an evidence-tracked tape semantics using the monadic-core-to-evidenced-frame pipeline (and its induced realizability tripos), obtaining a higher-order logic in which entailments are witnessed by uniform evidence transformers. Quantitative statements are recovered by interpretation: once a tape measure is fixed, probabilities and expectations arise by extracting numerical summaries from tape-indexed predicates, and entailments yield sound inequalities, with an almost-sure quotient supporting probability-one reasoning. We also study intensional principles that are lost at the level of laws, including proof-relevant transport along realizable tape-rewiring maps and a canonical splitting discipline for stream tapes enforcing independent draws. Finally, we relate tape-based reasoning to an extensional law semantics via pushforward, isolating a probability-one must abstraction as a sound summary of tape-based proofs.
@InProceedings{cohen_et_al:LIPIcs.FSCD.2026.13,
author = {Cohen, Liron and Samara, Tomer},
title = {{Evidence-Tracked Tape Semantics for Probabilistic Computation}},
booktitle = {11th International Conference on Formal Structures for Computation and Deduction (FSCD 2026)},
pages = {13:1--13:20},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-433-8},
ISSN = {1868-8969},
year = {2026},
volume = {378},
editor = {Pfenning, Frank},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.FSCD.2026.13},
URN = {urn:nbn:de:0030-drops-263633},
doi = {10.4230/LIPIcs.FSCD.2026.13},
annote = {Keywords: probabilistic programming, random tapes, realizability, evidenced frames, program logic, monadic combinatory algebras}
}