epdf.pub_the-nuts-and-bolts-of-proofs-third-edition-an-intr

List of Symbols
A function/is said to be:
1. increasing if for every two real numbers xi and X2 such that xi<X2,
it follows that
/(^i) </fe).
2. decreasing if for every two real numbers xi and X2 such that xi < xj,
it follows that
/(Xi)>/(X2).
3. nondecreasing if for every two real numbers xi and X2 such that xi < X2,
it follows that
f(Xl)<f(X2).
4. nonincreasing if for every two real numbers xi and X2 such that xi < X2,
it follows that
f(xO>f(X2).
5. odd if/(-x) = -fix) for all x.
6. even if/(—x) =/(x) for all x.
7. one-to-one if for every two real numbers xi and X2 such that xi 7^ X2,
it follows that/(xi) 7^/(x2).
8. onto if for every value y there is at least one value x such that /(x) = y.