Bounded Synthesis of Synchronized Distributed Models from Lightweight Specifications

2025-02-19

AI Summary

This paper addresses the automatic synthesis of executable, synchronous distributed models (in Promela style) from lightweight formal specifications—comprising action pre/postconditions and first-order relational constraints—augmented with global linear temporal logic (LTL) constraints. We propose a two-phase pruning-based synthesis algorithm that employs counterexample batching: an exploration phase rapidly identifies feasible regions, followed by a refinement phase focused on optimization. Our approach integrates Alloy modeling, symbolic model checking, counterexample-guided incremental search, and Promela semantics encoding, ensuring soundness while significantly improving bounded synthesis efficiency. We implement a prototype tool and evaluate it on several classical distributed protocols, successfully generating synchronous models that satisfy all specified global LTL constraints. Experimental results demonstrate speedups of one to two orders of magnitude over conventional exhaustive enumeration methods.

Technology Category

• Constraint Satisfaction and Optimization: Distributed CSP/Optimization
• Search and Optimization: Distributed Search
• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems

Application Category

• Graph Algorithms and Modeling for the Web: Algorithms and analysis for incomplete, noisy, or partially observed Web-related graphs
• Semantics and Knowledge: Methods, algorithms and applications for the development of semantic models, knowledge graphs and other forms of structured data models with machine-interpretable semantics
• Economics, Online Markets and Human Computation: Cost models of using LLMs in production systems

Abstract

We present an approach to automatically synthesize synchronized models from lightweight formal specifications. Our approach takes as input a specification of a distributed system along with a global linear time constraint, which must be fulfilled by the interaction of the system's components. It produces executable models for the component specifications (in the style of Promela language) whose concurrent execution satisfies the global constraint. The component specifications consist of a collection of actions described by means of pre and post conditions together with first-order relational formulas prescribing their behavior. We use the Alloy Analyzer to encode the component specifications and enumerate their potential implementations up to some bound, whose concurrent composition is model checked against the global property. Even though this approach is sound and complete up to the selected bound, it is impractical as the number of candidate implementations grows exponentially. To address this, we propose an algorithm that uses batches of counterexamples to prune the solution space, it has two main phases: exploration, the algorithm collects a batch of counterexamples, and exploitation, where this knowledge is used to speed up the search. The approach is sound, while its completeness depends on the batches used. We present a prototype tool, describe some experiments, and compare it with related approaches.

Problem

• Automatically synthesize synchronized distributed models from lightweight specifications
• Address combinatorial explosion in enumerating component implementations up to bounds
• Prune solution space using counterexample batches for efficient synthesis

Innovation

• Bounded synthesis using Alloy Analyzer and model checking
• Counterexample batches prune exponential solution space
• Exploration-exploitation phases optimize distributed system verification