*[The book version of this post at https://terrytao.wordpress.com/books/an-introduction-to-measure-theory/ contains links to such examples in other sections of the book. -T.]*

Please let me know if I misunderstood! I know that some mathematicians occasionally use the proper subset symbol to mean “a subset of or equal to”, much to the chagrin of those raised by baby and/or adolescent Rudin (the text, not the man).

]]>“In a similar spirit, to show that two sets E and F are equal, try proving that and $E \subset B$ and $B \subset E$.”

I believe that it’d be the following instead:

“In a similar spirit, to show that two sets E and F are equal, try proving that $E \subseteq B$ and $B \subseteq E$.

Regards.

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