Baily–Borel compactification

The Baily–Borel compactification is a method used in the field of algebraic geometry and arithmetic geometry to compactify certain types of locally symmetric spaces, particularly those associated with Hermitian symmetric domains. It is named after the mathematicians William Baily and Armand Borel, who introduced the concept. ### Context and Motivation In many situations, particularly in number theory and the theory of modular forms, one deals with spaces that are not compact.