In a groundbreaking stride toward harmonizing advanced mathematical research with cutting-edge computational technology, two leading figures from the University of Bonn’s Hausdorff Center for Mathematics (HCM) have secured a prestigious Synergy Grant from the European Research Council (ERC). Professors Christoph Thiele and Floris van Doorn have been awarded a total of 6.4 million euros to propel their innovative initiative, “Harmonic Analysis with Lean Formalization” (HALF), over the coming six years. This ambitious project aims to revolutionize the way complex mathematical proofs are constructed, verified, and applied in real time through the development and integration of the Lean programming language, which is rapidly emerging as a vital tool in the formalization of mathematics.
At the heart of the HALF project lies a profound ambition: to translate the intricate and often abstract domain of harmonic analysis into a form that computers can not only understand but also verify autonomously. Harmonic analysis, pivotal in the study of functions and the transformation of signals, encompasses both multilinear and nonlinear operators—a realm ripe with unresolved questions that resonate across numerous mathematical disciplines and interdisciplinary fields including ergodic theory and quantum information processing. The outputs of this project are poised to redefine the contours of academic research by enabling mathematicians to authenticate proofs with computational precision, a feat that could dramatically accelerate the pace of discovery and reduce human error in the verification process.
The use of Lean as a foundational tool for formalization marks a significant technological advancement. Lean, characterized by its user-friendly yet highly expressive syntax, offers a robust environment where mathematicians can encode proofs thoroughly and verify them with relative efficiency. This represents a crucial step forward from current practices, where formal proof verification tends to be labor-intensive and limited primarily to simpler mathematical cases, often relegated to educational settings rather than advanced research. The HALF initiative represents the first comprehensive effort to embed this methodology deeply into the complex fabric of contemporary mathematical research.
Professors van Doorn and Thiele bring together complementary expertise that is key to navigating the multidimensional challenges of this project. Van Doorn, a pioneer in the formalization movement and a principal architect of Mathlib—an evolving library dedicated to encapsulating fundamental mathematical knowledge for automated proof—joins forces with Thiele, who is renowned for his pioneering work in harmonic analysis. Their collaboration is anchored at the intersection of mathematical theory, computational innovation, and the growing field of artificial intelligence (AI), promising advancements that extend well beyond pure mathematics into applied sciences and technological sectors.
One of the most compelling motivations behind the HALF project is its potential to transform the peer review and publication process. Traditionally, the validation of complex mathematical proofs relies heavily on expert human scrutiny, an approach susceptible to oversight and constrained by human limitations. Van Doorn envisions a future where computational verification precedes and complements human review, dramatically enhancing the reliability and efficiency of scientific dissemination. This paradigm shift could also pave the way for AI-generated proofs, where formalization by machines becomes an integral part of verifying and trusting AI contributions without the need for exhaustive manual intervention.
The interdisciplinary ramifications of this work are substantial. Emerging fields such as AI-driven discovery methods and quantum computing stand to benefit enormously from reliable, automated proof verification mechanisms. As AI systems increasingly undertake tasks that require rigorous logical consistency and faultless reasoning—in part through frameworks like Lean—the HALF project will provide the essential scaffolding to ensure these systems produce sound and verifiable outcomes. The development of specialized training materials aimed at researchers and AI practitioners underscores the proactive approach taken by the Bonn team to embed formal verification deeply into future scientific workflows.
A critical proof of concept emerged from a pilot project conducted prior to the awarding of the Synergy Grant. Thiele’s research group identified a novel harmonic analysis result that was well-suited for formalization, coinciding with the formal verification of a classical theorem originally posited by Lennart Carleson in 1966. This effort required intensive collaboration and drew support from a global community of Lean enthusiasts, culminating far more swiftly than anticipated. The success of this pilot not only validated the feasibility of the approach but also offered a compelling blueprint to scale these activities internally within the team at Bonn under the HALF project’s auspices.
The technical endeavor to encapsulate such complex mathematical constructs within the Lean environment poses numerous challenges. Multilinear and nonlinear operators are known for their algebraic and analytic subtleties, demanding precise encoding to preserve mathematical rigor without sacrificing computational tractability. Navigating this balance necessitates novel algorithmic strategies, improvements in formal languages, and enhanced collaboration tools. The HALF team’s methodology involves iterative refinement, deploying continuous feedback loops between discoveries in harmonic analysis and their formal representations, ensuring that the formalizations are both faithful and computationally elegant.
Beyond the immediate scientific goals, the researchers foresee broader impacts on educational and scientific communities worldwide. The Mathlib library serves as a foundational asset, providing a standard repository of verified mathematical knowledge that supports a wide range of educational levels—from foundational concepts to advanced university topics. Expanding this corpus with HALF’s contributions promises to nurture a new generation of scholars adept in both theory and computational formalism, fostering a culture in which mathematical research and computer verification are deeply intertwined.
In terms of academic pedigree and personal accolades, both researchers have distinguished themselves through extraordinary accomplishments. Christoph Thiele’s academic journey from German institutions to prestigious appointments, including a professorship at UCLA and the Hausdorff Chair at Bonn, has been marked by prestigious awards such as the Salem Prize and the Humboldt Research Prize. His contributions have significantly shaped the modern landscape of harmonic analysis. Meanwhile, Floris van Doorn, who completed his doctorate at Carnegie Mellon University, is recognized internationally for advancing formalization methods in Lean and leading critical collaborations within the Mathlib project. His remarkable achievements have been honored with the Skolem Award, underscoring his influential role in the formal methods community.
Looking forward, the HALF project represents a pathbreaking synthesis between age-old mathematical inquiry and avant-garde computational technology. It seeks to democratize and expedite the verification of mathematical truths, setting the stage for a future in which proofs are not only human-made but machine-verified and AI-augmented. By bridging these worlds, the project aspires to establish harmonic analysis as a flagship domain for formal mathematical proof and to catalyze an evolution in how knowledge is generated, validated, and shared in the 21st century.
Subject of Research:
Harmonic analysis formalization using Lean programming language, focused on multilinear and nonlinear operators and their applications in various fields including ergodic theory and quantum information.
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Web References:
https://mediasvc.eurekalert.org/Api/v1/Multimedia/56a51cf2-c4a9-48ae-a644-898a4888504c/Rendition/low-res/Content/Public
Image Credits:
Volker Lannert/Uni Bonn
Keywords:
Harmonic Analysis, Lean Formalization, Synergy Grant, European Research Council, Mathematical Proof Verification, Formal Proof Systems, Artificial Intelligence, Mathlib, Nonlinear Operators, Multilinear Operators, Quantum Information Processing, Ergodic Theory

