Formal Conjectures: An Open and Evolving Benchmark for Verified Discovery in Mathematics. - Moritz Firsching; Paul Lezeau; Salvatore Mercuri; Miklós Z. Horváth; Yaël Dillies; Calle Sönne; Eric Wieser; Fred Zhang; Thomas Hubert; Blaise Agüera y Arcas; Pushmeet Kohli (CoRR, 2026)