During April 2026, Pion Chan enhanced the leanprover-community/mathlib4 repository by expanding support for Sl2 Lie algebra representations. They implemented new lemmas in Lean, including tools for handling powers of the toEnd function and establishing the existence of primitive vectors, which provide foundational capabilities for representation-theoretic proofs. The work involved splitting a larger pull request into two focused commits, improving maintainability and facilitating code review. Collaborating with other contributors, Pion Chan’s updates strengthened the mathematical framework for Sl2 modules, enabling more robust theorem proving and streamlined workflows. Their contributions demonstrated depth in Lean, mathematics, and formal verification.