Breaking the Mold: Nonlinear Ranking Function Synthesis Without Templates

Fuente: arXiv
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Auteurs principaux: Zhu, Shaowei, Kincaid, Zachary
Format: Preprint
Publié: 2024
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author Zhu, Shaowei
Kincaid, Zachary
author_facet Zhu, Shaowei
Kincaid, Zachary
contents This paper studies the problem of synthesizing (lexicographic) polynomial ranking functions for loops that can be described in polynomial arithmetic over integers and reals. While the analogous ranking function synthesis problem for linear arithmetic is decidable, even checking whether a given function ranks an integer loop is undecidable in the nonlinear setting. We side-step the decidability barrier by working within the theory of linear integer/real rings (LIRR) rather than the standard model of arithmetic. We develop a termination analysis that is guaranteed to succeed if a loop (expressed as a formula) admits a (lexicographic) polynomial ranking function. In contrast to template-based ranking function synthesis in real arithmetic, our completeness result holds for lexicographic ranking functions of unbounded dimension and degree, and effectively subsumes linear lexicographic ranking function synthesis for linear integer loops.
format Preprint
id arxiv_https___arxiv_org_abs_2409_18063
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Breaking the Mold: Nonlinear Ranking Function Synthesis Without Templates
Zhu, Shaowei
Kincaid, Zachary
Programming Languages
Logic in Computer Science
This paper studies the problem of synthesizing (lexicographic) polynomial ranking functions for loops that can be described in polynomial arithmetic over integers and reals. While the analogous ranking function synthesis problem for linear arithmetic is decidable, even checking whether a given function ranks an integer loop is undecidable in the nonlinear setting. We side-step the decidability barrier by working within the theory of linear integer/real rings (LIRR) rather than the standard model of arithmetic. We develop a termination analysis that is guaranteed to succeed if a loop (expressed as a formula) admits a (lexicographic) polynomial ranking function. In contrast to template-based ranking function synthesis in real arithmetic, our completeness result holds for lexicographic ranking functions of unbounded dimension and degree, and effectively subsumes linear lexicographic ranking function synthesis for linear integer loops.
title Breaking the Mold: Nonlinear Ranking Function Synthesis Without Templates
topic Programming Languages
Logic in Computer Science
url https://arxiv.org/abs/2409.18063