In Shelah's model of no Borel lifting of the measure algebra we show that there is a σ-complete Boolean algebra of cardinality 2ω that is not a quotient of a complete Boolean algebra. By Stone duality ...

Algebraic structures form the backbone of many modern mathematical disciplines, providing abstract frameworks that capture the essence of operations and relations. Duality theory, in this context, ...

This paper presents duality results between categories of neighbourhood frames for modal logic and categories of modal algebras (i.e. Boolean algebras with an additional unary operation). These ...