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POPL 2019
Sun 13 - Sat 19 January 2019 Cascais, Portugal
Mon 14 Jan 2019 11:30 - 12:00 at Sala III - Decision Procedures Chair(s): Kedar Namjoshi

We present Dryad_dec, a decidable logic that allows reasoning about tree data-structures with measurements. This logic supports user-defined recursive measure functions based on Max or Sum, and recursive predicates based on these measure functions, such as AVL trees or red-black trees. We prove that the logic’s satisfiability is decidable. The crux of the decidability proof is a small model property which allows us to reduce the satisfiability of Dryad_dec to quantifier-free linear arithmetic theory which can be solved efficiently using SMT solvers. We also show that Dryad_dec can encode a variety of verification and synthesis problems, including natural proof verification conditions for functional correctness of recursive tree-manipulating programs, legality conditions for fusing tree traversals, synthesis conditions for conditional linear-integer arithmetic functions. We developed the decision procedure and successfully solved 220+ Dryad_dec formulae raised from these application scenarios, including verifying functional correctness of programs manipulating AVL trees, red-black trees and treaps, checking the fusibility of height-based mutually recursive tree traversals, and counterexample-guided synthesis from linear integer arithmetic specifications. To our knowledge, Dryad_dec is the first decidable logic that can solve such a wide variety of problems requiring flexible combination of measure-related, data-related and shape-related properties for trees.

slides (vmcai.ppsx)2.79MiB

Mon 14 Jan
Times are displayed in time zone: Greenwich Mean Time : Belfast change

11:00 - 12:30: Decision ProceduresVMCAI at Sala III
Chair(s): Kedar NamjoshiBell Labs, Nokia
11:00 - 11:30
Solving and Interpolating Constant Arrays Based on Weak Equivalences
Jochen HoenickeUniversität Freiburg, Tanja SchindlerUniversity of Freiburg
11:30 - 12:00
A Decidable Logic for Tree Data-Structures with Measurements
Xiaokang QiuPurdue University, Yanjun WangPurdue University
File Attached
12:00 - 12:30
A Practical Algorithm for Structure Embedding
Charlie MurphyPrinceton University, Zachary KincaidPrinceton University
File Attached