Let $t \mapsto e^t$ be the D1932: Standard natural real exponential function.
The softmax function with respect to $N \in 2, 3, 4, \ldots$ is the D4363: Euclidean real function \begin{equation} \mathbb{R}^N \to (0, 1)^N, \quad x \mapsto \frac{1}{\sum_{n = 1}^N e^{x_n}} \left( e^{x_1}, \ldots, e^{x_N} \right) \end{equation}