CSLib: The Lean Computer Science Library

2026-02-04

AI Summary

This work addresses the lack of a systematic, formalized knowledge base for computer science in Lean, which has hindered its adoption in education, research, and large-scale verification. To bridge this gap, we present CSLib—the first open-source library of formalized theorems and data structures specifically designed for computer science, built upon the Lean proof assistant and dependent type theory. CSLib establishes a reusable and composable formal infrastructure that significantly expands Lean’s foundational knowledge base in computer science. By providing a comprehensive and extensible collection of verified components, CSLib enables effective collaboration between human developers and AI systems in constructing large-scale formally verified software, thereby advancing the broader application and accessibility of formal methods within the field.

Technology Category

• Knowledge Representation and Reasoning: Automated Reasoning and Theorem Proving
• Constraint Satisfaction and Optimization: Satisfiability Modulo Theories
• Cognitive Modeling & Cognitive Systems: Conceptual Inference and Reasoning

Application Category

• Semantics and Knowledge: Scalable techniques for the creation, curation, publication, maintenance, and consumption of large, Web-based, structured, reusable, knowledge graphs and ontologies
• Systems and Infrastructure for Web, Mobile and WoT: Applied ML and AI for Web-based mobile applications
• Graph Algorithms and Modeling for the Web: Foundation models and LLMs for Web-related graphs

Abstract

We introduce CSLib, an open-source framework for proving computer-science-related theorems and writing formally verified code in the Lean proof assistant. CSLib aims to be for computer science what Lean's Mathlib is for mathematics. Mathlib has been tremendously impactful: it is a key reason for Lean's popularity within the mathematics research community, and it has also played a critical role in the training of AI systems for mathematical reasoning. However, the base of computer science knowledge in Lean is currently quite limited. CSLib will vastly enhance this knowledge base and provide infrastructure for using this knowledge in real-world verification projects. By doing so, CSLib will (1) enable the broad use of Lean in computer science education and research, and (2) facilitate the manual and AI-aided engineering of large-scale formally verified systems.

Problem

• formal verification
• proof assistant
• computer science library
• Lean
• verified code

Innovation

• CSLib
• formal verification
• Lean proof assistant
• computer science library
• AI-aided verification