### Math Miscellany

\cdots
The \cdots command produces a horizontal ellipsis where the dots are raised to the center of the line.
\ddots
The \ddots command produces a diagonal ellipsis.
\frac
\frac{num}{den} The \frac command produces the fraction num divided by den.
\ldots
The \ldots command produces an ellipsis. This command works in any mode, not just math mode.
\overbrace
\overbrace{text} The \overbrace command generates a brace over text.
\overline
\overline{text} The \overline command causes the argument text to be overlined.
\sqrt
\sqrt[root]{arg} The \sqrt command produces the square root of its argument. The optional argument, root, determines what root to produce, i.e., the cube root of x+y would be typed as $\sqrt[3]{x+y}$.
\underbrace
\underbrace{text} The \underbrace command generates text with a brace underneath.
\underline
\underline{text} The \underline command causes the argument text to be underlined. This command can also be used in paragraph and LR modes.
\vdots
The \vdots command produces a vertical ellipsis.