## Math Problem Solving Group Posting Guidelines

The MathPSG emailing list is moderated. Postings sent to the list will not be automatically forwarded to its members, they must await approval by the moderator. These are the posting guidelines.

1. The topic must be consistent with the goals and activities of the Northwestern University Math Problem Solving Group.

2. When posting a solution (or hint, or suggestion...) concerning a new problem, include a statement of the problem - not just a reference.

3. Give others a chance to participate and learn. Don't just send a final complete solution to a problem. If you have a solution, announce it and send first some hints on how you arrived to it, inviting others to work the problem by themselves. If you send a partial or complete solution it is a good idea to add some narrative illustrating your thoughts while working on the problem, so that others can take advantage of your learning experience.

4. Postings must be carefully written and easy to read. Although linguistic limitations are understandable and expected, try to use complete sentences written in correct English and check your messages for spelling mistakes.

5. Write your messages in plain text (e.g. no html formatting) and without attachments. If the solution to a problem cannot be easily expressed using plain text then two possible solutions are:

• Post it in a public repository and send a link to it.

• Send the email with attachment directly to the list moderator rather than the list (the moderator can post the document on a public space and then distribute a link).

These are some recommendations and examples about how to write mathematical formulas in plain text:

• Arithmetic expressions, relations . . . :
  addition/subtraction: a + b, a - b.
multiplication: a b, a * b.
division: a/b.
powers, superscripts: x^y = x raised to the y-th power, or x superscript y.
subscripts: x_n, x_{n}, x[n] = x subscript n.
relations: > (greater than), < (less than), >= (greater than or equal to),
=< (less than or equal to), != (different), <> (different).


• Functions:
  sqrt(x) = square root of x
sin(x) = sine of x


• Sums, products, integrals, limits...
  sum for n=a to b of a_n
product for n=a to b of a_n
integral between a and b of f(x) dx
limit as x -> infinity of f(x)


• Special constants, Greek letters, etc.: just write the name: e, pi, alpha, aleph, Omega, infinity...

• Sets: Some especial sets like the set of real numbers are usually written with a letter in blackboard font. In plain text use the same letter, perhaps clarifying its meaning, e.g.: "for x in R (real numbers)..."
Example of set: {x in R | x > 3} = set of elements x in R such that x > 3.

Other conventions like TeX, Maple, Mathematica, etc., are also acceptable; e.g.:

 lim_{n \to \infty} 1/n = 0


(but keep in mind that some readers may not be familiar with them.)