Alessandra contributed to the leanprover-community/mathlib4 repository by strengthening the Multiset powerset theory and enhancing List.Subperm utilities. She focused on formal verification and theorem proving in Lean, delivering formal proofs for properties such as injectivity, monotonicity, and strict monotonicity of the Multiset.powerset function. Her work established a precise size relationship between powersets and their underlying multisets, improving the safety and expressiveness of multiset reasoning. Additionally, Alessandra extended List.Subperm with new lemmas and theorems, facilitating more robust proof composition for list permutation logic. The depth of her contributions reflects strong expertise in functional programming and formal methods.