Denotational Foundations for Expected Cost Analysis

Fuente: arXiv
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Autor principal: de Amorim, Pedro H. Azevedo
Formato: Preprint
Publicado: 2024
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author de Amorim, Pedro H. Azevedo
author_facet de Amorim, Pedro H. Azevedo
contents Reasoning about the cost of executing programs is one of the fundamental questions in computer science. In the context of programming with probabilities, however, the notion of cost stops being deterministic, since it depends on the probabilistic samples made throughout the execution of the program. This interaction is further complicated by the non-trivial interaction between cost, recursion and evaluation strategy. In this work we introduce $\mathbf{cert}$: a Call-By-Push-Value (CBPV) metalanguage for reasoning about probabilistic cost. We equip $\mathbf{cert}$ with an operational cost semantics and define two denotational semantics -- a cost semantics and an expected-cost semantics. We prove operational soundness and adequacy for the denotational cost semantics and a cost adequacy theorem for the expected-cost semantics. We formally relate both denotational semantics by stating and proving a novel \emph{effect simulation} property for CBPV. We also prove a canonicity property of the expected-cost semantics as the minimal semantics for expected cost and probability by building on recent advances on monadic probabilistic semantics. Finally, we illustrate the expressivity of $\mathbf{cert}$ and the expected-cost semantics by presenting case-studies ranging from randomized algorithms to stochastic processes and show how our semantics capture their intended expected cost.
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id arxiv_https___arxiv_org_abs_2402_01009
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Denotational Foundations for Expected Cost Analysis
de Amorim, Pedro H. Azevedo
Programming Languages
Logic in Computer Science
Reasoning about the cost of executing programs is one of the fundamental questions in computer science. In the context of programming with probabilities, however, the notion of cost stops being deterministic, since it depends on the probabilistic samples made throughout the execution of the program. This interaction is further complicated by the non-trivial interaction between cost, recursion and evaluation strategy. In this work we introduce $\mathbf{cert}$: a Call-By-Push-Value (CBPV) metalanguage for reasoning about probabilistic cost. We equip $\mathbf{cert}$ with an operational cost semantics and define two denotational semantics -- a cost semantics and an expected-cost semantics. We prove operational soundness and adequacy for the denotational cost semantics and a cost adequacy theorem for the expected-cost semantics. We formally relate both denotational semantics by stating and proving a novel \emph{effect simulation} property for CBPV. We also prove a canonicity property of the expected-cost semantics as the minimal semantics for expected cost and probability by building on recent advances on monadic probabilistic semantics. Finally, we illustrate the expressivity of $\mathbf{cert}$ and the expected-cost semantics by presenting case-studies ranging from randomized algorithms to stochastic processes and show how our semantics capture their intended expected cost.
title Denotational Foundations for Expected Cost Analysis
topic Programming Languages
Logic in Computer Science
url https://arxiv.org/abs/2402.01009