Gimel function

In axiomatic set theory, the gimel function is the following function mapping cardinal numbers to cardinal numbers:

${\displaystyle \gimel \colon \kappa \mapsto \kappa ^{\mathrm {cf} (\kappa )}}$

where cf denotes the cofinality function; the gimel function is used for studying the continuum function and the cardinal exponentiation function. The symbol ${\displaystyle \gimel }$ is a serif form of the Hebrew letter gimel.