Results involving entire functions include the following, as examples.

Many important problems involve functions of several variables.

The match rules assign different values for matches involving functions and relations.

Similarly, animals are very likely to do things not in the script, generally involving bodily functions.

All these problems involve functions (typically multivariate) of a real or complex variable.

It also frequently appears in various integrals involving Gaussian functions.

He said he thought that any staff cuts would involve "back-room functions."

Clearly the approach via (1.1) and (3.1) does not involve characteristic functions.

Formal proofs usually follow a different approach which involve characteristic functions.

A second instance involves functions of a motor variable where arguments are split-complex numbers.