A truth function is a function that returns one of two values, one of which is interpreted as “true,” and the other which is interpreted as “false”. Typically either “T” and “F” are used, or “1” and “0”, respectively. Using the latter, we can write

defines a truth function $f$. That is, $f$ is a mapping from any number ($n$) of true/false (0 or 1) values to a single value, which is 0 or 1.