arrows with text

There are several ways to place text above/below arrows or arrows above/below text.

First there are \overrightarrow ( $\overrightarrow{text}$) and \overleftarrow ( $\overleftarrow{text}$). In the amsmath package these commands are reimplemented (though math mode is needed now) and extended with the command \overleftrightarrow and it is also possible to get the arrow under the text with \under...arrow.

In amsmath it is also possible top use \xrightarrow and \xleftarrow that extend automatically:

$$A\xleftarrow{n+\mu-1}B \xrightarrow[T]{n\pm i-1}C$$

Generated by A\xleftarrow{n+\mu-1}B \xrightarrow[T]{n\pm i-1}C.

It is also possible to place a symbol above or below something else with the amsmath commands \overset and \underset. For example: \overset{x}{\rightarrow} ( $\overset{x}{\rightarrow}$).

This information and more can be found in the file /usr/local/share/texmf-dist/doc/latex/amsmath/amsldoc.pdf which should come with the latex distribution.