Invariant inference via quantified separation

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Abstract/Contents

Abstract
Quantified first-order formulas, often with quantifier alternations, are increasingly used in the verification of complex systems. While automated theorem provers for first-order logic are becoming more robust, until recently invariant inference tools that handle quantifiers were restricted to purely universal formulas. We define and analyze first-order quantified separators and their application to inferring quantified invariants with alternations. A separator for a given set of positively and negatively labeled structures is a formula that is true on positive structures and false on negative structures. We investigate the problem of finding a separator from the class of formulas in prenex normal form with a bounded number of quantifiers and show this problem is NP-complete by reduction to and from SAT. Based on this computational primitive, we present a new PDR/IC3-based algorithm for finding inductive invariants with quantifier alternations. We tackle scalability issues that arise due to the large search space of quantified invariants by combining a breadth-first search strategy and a new syntactic form for quantifier-free bodies. The breadth-first strategy prevents inductive generalization from getting stuck in regions of the search space that are expensive to search and focuses instead on lemmas that are easy to discover. The new syntactic form is well-suited to lemmas with quantifier alternations by allowing both limited conjunction and disjunction in the quantifier-free body, while carefully controlling the size of the search space. We evaluate both separation itself and our combined invariant inference algorithm on a benchmark of primarily distributed protocols, including complex Paxos variants. We demonstrate separation can be solved in practice, and that our inference algorithm can solve more of the most complicated examples than other state-of-the-art techniques.

Description

Type of resource text
Form electronic resource; remote; computer; online resource
Extent 1 online resource.
Place California
Place [Stanford, California]
Publisher [Stanford University]
Copyright date 2022; ©2022
Publication date 2021; 2021
Issuance monographic
Language English

Creators/Contributors

Author Koenig, Jason Richard
Degree supervisor Aiken, Alexander
Thesis advisor Aiken, Alexander
Thesis advisor Barrett, Clark
Thesis advisor Trippel, Caroline
Degree committee member Barrett, Clark
Degree committee member Trippel, Caroline
Associated with Stanford University, Computer Science Department

Subjects

Genre Theses
Genre Text

Bibliographic information

Statement of responsibility Jason Richard Koenig.
Note Submitted to the Computer Science Department.
Thesis Thesis Ph.D. Stanford University 2022.
Location https://purl.stanford.edu/vx350kj7751

Access conditions

Copyright
© 2022 by Jason Richard Koenig
License
This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).

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