Math Terms

I just got an awesome email from one of the professors.  This guy is one of the main statisticians of the department, and so is even more likely to use math terminology than the average economist:

Dear Grad students,

...

If you are a member of the union of the sets {students not on the market this year}

and {students who received my test message described above}, please ignore

this message.  On the other hand, if you belong to the compliment [sic] of the union of

these sets, let me know.

Best regards,

In mathematics, 'union' is a fancy way of saying 'or'.  The union of two groups of people is anyone who fits in either group.*  'Complement' is a fancy way of saying 'not'.  The complement of a group is anyone that does not fit in that group.

The funny thing is that this mathematical language was an accurate and precise way of communicating what he meant, and that it will be easily understood by everyone who gets the email.

This also illustrates an important thing about math.  Learning math is a lot like learning a foreign language.  You have to be immersed in it, and use it daily, and communicate with people who know it well.  You get much better at math when you are in a community of people who know math and use it in everyday language.  Our educational system teaches math almost as badly as it teaches foreign languages, and for similar reasons.

*Conversely, 'intersection' means 'and'.  You are part of the intersection of two groups if you fit in both groups.