/sci/ - Science & Math

>>15520238
That definition is taken straight out of papa Rudin and the entire rest of the first chapter is dedicated to understanding what this concept is about in terms of measurable spaces, with plenty of exercises on the definition of a sigma algebra, such as the very first exercise: "Does there exist an infinite sigma-algebra which has only countably many members?" Lots of what you're asking for are things you are expected to be able to create for yourself in a process of active reading. It builds mathematical strength and maturity.