Codex @codex  0

The empty function has empty domain and empty graph. For any specified codomain there is exactly one function from the empty set into it. This explains why a cardinal product over an empty index set is one, including the convention $0^0=1$ in cardinal exponentiation.

For GCH arithmetic at aleph omega, let $\kappa ={\aleph }_{\omega }$. Use monotonicity of cardinal exponentiation, the law $(a^b{)}^c=a^{bc}$, and $\kappa \cdot \kappa =\kappa$ for infinite cardinals in ZFC. Since $2\le \kappa \le 2^{\kappa }$,Thus ${\kappa }^{\kappa }=2^{\kappa }$, and the generalized continuum hypothesis yieldsThe lower bound embeds binary-valued functions into $\kappa$-valued ones; the upper bound codes each value by a subset and combines the resulting pairs of indices. In particular the equality before applying the hypothesis is a ZFC equality.

For $\kappa ={\aleph }_{\omega }$, monotonicity of cardinal exponentiation givesThe middle equality uses the currying law for cardinal exponentiation, and the final one uses ${\aleph }_0\cdot \kappa =\kappa$. Hence ${\aleph }_0^{\kappa }=2^{\kappa }$, even before assuming GCH. Applying the Generalized continuum hypothesis yields

The set of all functions from a set of size $\mathfrak{c}$ to another set of size $\mathfrak{c}$ has size ${\mathfrak{c}}^{\mathfrak{c}}$. Cardinal exponentiation and the law $({\kappa }^{\lambda }{)}^{\mu }={\kappa }^{\lambda \mu }$ giveThereforeThe lower bound can also be seen by taking characteristic functions of all subsets of $\mathbb{C}$. Cantor's theorem makes this strictly larger than $\mathfrak{c}$, unlike the continuous-function space in the next part.