How to Build a Formal Mathematical Library in which Communication is Prioritized over Certification: An Extended Abstract William M. Farmer 2026 Abstract Formal mathematics is mathematics done within the framework of a formal logic. The standard approach to formal mathematics, in which mathematics is done with a proof assistant and all details are formally proved and mechanically checked, focuses on certification. In contrast, the free approach to formal mathematics, an alternative to the standard approach that is free of the obligation to formally prove and mechanically check all details using a proof assistant, focuses on communication and accessibility. A formal mathematical library (FML) is a repository of mathematical knowledge expressed within a formal logic and organized as a network of interconnected axiomatic theories. This talk presents the free approach, describes how a communication-oriented FML can be built using the free approach, and ends by encouraging the mathematics software community to develop the logics and software needed to build communication-oriented FMLs.