ThmDex – An index of mathematical definitions, results, and conjectures.
F13511
Formulation 6
Let $\alpha, \beta \in (0, \infty)$ each be a D5407: Positive real number such that
(i) $x \mapsto \lfloor x \rfloor$ is the D764: Real-integer floor function
(ii) \begin{equation} N := \lfloor \alpha \rfloor \end{equation}
(iii) $T_1, \, \ldots, \, T_N \overset{d}{=} \text{Exponential}(\beta)$ are each an D214: Exponential random positive real number
(iv) $A \overset{d}{=} \text{Alpha}(\alpha - N, \beta)$ is an D6332: Alpha random positive real number
(v) $A, T_1, \, \ldots, \, T_N$ is an D2713: Independent random collection
A D5722: Random positive real number $X \in \text{Random}(0, \infty)$ is a gamma random positive real number with parameter $(\alpha, \beta)$ if and only if \begin{equation} X \overset{d}{=} A + \sum_{n = 1}^N T_n \end{equation}