==================== Sets ==================== .. warning:: Under progress! .. note:: Most of the definitions and notation in the section are based on [rudin]_ If :latex:`$A \supset B$` and :latex:`$B \supset A$` we write :latex:`$A = B$`; otherwise :latex:`$A \neq B$`. .. [rudin] `Principles of Mathematical Analysis (3rd ed)`:title:, by Walter Rudin. McGraw-Hill, 1976