Abstract Hidden Markov Models: a monadic account of quantitative information flow

Hidden Markov Models, HMM's, are mathematical models of Markov processes with state that is hidden, but from which information can leak. They are typically represented as 3-way joint-probability distributions. We use HMM's as denotations of probabilistic hidden-state sequential programs:...

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Main Authors: Annabelle McIver, Carroll Morgan, Tahiry Rabehaja
Format: Article
Language:English
Published: Logical Methods in Computer Science e.V. 2019-03-01
Series:Logical Methods in Computer Science
Subjects:
Online Access:https://lmcs.episciences.org/3851/pdf
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author Annabelle McIver
Carroll Morgan
Tahiry Rabehaja
author_facet Annabelle McIver
Carroll Morgan
Tahiry Rabehaja
author_sort Annabelle McIver
collection DOAJ
description Hidden Markov Models, HMM's, are mathematical models of Markov processes with state that is hidden, but from which information can leak. They are typically represented as 3-way joint-probability distributions. We use HMM's as denotations of probabilistic hidden-state sequential programs: for that, we recast them as `abstract' HMM's, computations in the Giry monad $\mathbb{D}$, and we equip them with a partial order of increasing security. However to encode the monadic type with hiding over some state $\mathcal{X}$ we use $\mathbb{D}\mathcal{X}\to \mathbb{D}^2\mathcal{X}$ rather than the conventional $\mathcal{X}{\to}\mathbb{D}\mathcal{X}$ that suffices for Markov models whose state is not hidden. We illustrate the $\mathbb{D}\mathcal{X}\to \mathbb{D}^2\mathcal{X}$ construction with a small Haskell prototype. We then present uncertainty measures as a generalisation of the extant diversity of probabilistic entropies, with characteristic analytic properties for them, and show how the new entropies interact with the order of increasing security. Furthermore, we give a `backwards' uncertainty-transformer semantics for HMM's that is dual to the `forwards' abstract HMM's - it is an analogue of the duality between forwards, relational semantics and backwards, predicate-transformer semantics for imperative programs with demonic choice. Finally, we argue that, from this new denotational-semantic viewpoint, one can see that the Dalenius desideratum for statistical databases is actually an issue in compositionality. We propose a means for taking it into account.
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spelling doaj.art-d7c385d3b33b4485ba84a65c73b4b8752024-03-08T10:27:57ZengLogical Methods in Computer Science e.V.Logical Methods in Computer Science1860-59742019-03-01Volume 15, Issue 110.23638/LMCS-15(1:36)20193851Abstract Hidden Markov Models: a monadic account of quantitative information flowAnnabelle McIverCarroll MorganTahiry RabehajaHidden Markov Models, HMM's, are mathematical models of Markov processes with state that is hidden, but from which information can leak. They are typically represented as 3-way joint-probability distributions. We use HMM's as denotations of probabilistic hidden-state sequential programs: for that, we recast them as `abstract' HMM's, computations in the Giry monad $\mathbb{D}$, and we equip them with a partial order of increasing security. However to encode the monadic type with hiding over some state $\mathcal{X}$ we use $\mathbb{D}\mathcal{X}\to \mathbb{D}^2\mathcal{X}$ rather than the conventional $\mathcal{X}{\to}\mathbb{D}\mathcal{X}$ that suffices for Markov models whose state is not hidden. We illustrate the $\mathbb{D}\mathcal{X}\to \mathbb{D}^2\mathcal{X}$ construction with a small Haskell prototype. We then present uncertainty measures as a generalisation of the extant diversity of probabilistic entropies, with characteristic analytic properties for them, and show how the new entropies interact with the order of increasing security. Furthermore, we give a `backwards' uncertainty-transformer semantics for HMM's that is dual to the `forwards' abstract HMM's - it is an analogue of the duality between forwards, relational semantics and backwards, predicate-transformer semantics for imperative programs with demonic choice. Finally, we argue that, from this new denotational-semantic viewpoint, one can see that the Dalenius desideratum for statistical databases is actually an issue in compositionality. We propose a means for taking it into account.https://lmcs.episciences.org/3851/pdfcomputer science - logic in computer science
spellingShingle Annabelle McIver
Carroll Morgan
Tahiry Rabehaja
Abstract Hidden Markov Models: a monadic account of quantitative information flow
Logical Methods in Computer Science
computer science - logic in computer science
title Abstract Hidden Markov Models: a monadic account of quantitative information flow
title_full Abstract Hidden Markov Models: a monadic account of quantitative information flow
title_fullStr Abstract Hidden Markov Models: a monadic account of quantitative information flow
title_full_unstemmed Abstract Hidden Markov Models: a monadic account of quantitative information flow
title_short Abstract Hidden Markov Models: a monadic account of quantitative information flow
title_sort abstract hidden markov models a monadic account of quantitative information flow
topic computer science - logic in computer science
url https://lmcs.episciences.org/3851/pdf
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