recovering the poisson process given a generator matrix

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We learned about generator (rate) matrices in class, and we showed how to retrieve the generator matrix given some transition matrix that represents a Poisson process. Is there a way to go in the other direction? Given a generator matrix, can I get the Poisson process? One way I see is to first recover the transition matrix, and argue that the transition matrix meets the definition of a Poisson process. Are there any other more rigorous arguments that could be used? I'm trying to contextualize what generator matrices are actually for and how they fit into the big picture of representing a process.

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A Poisson process, considered as a counting process is a continuous-time Markov chain with generator matrix of the form $$ \left( \begin{array}{ccccc} -\lambda & \lambda & 0 & 0 & 0 \\ 0 & -\lambda & \lambda & 0 & 0 \\ 0 & 0 & -\lambda & \lambda & 0 \\ 0 & 0 & 0 & -\lambda & \lambda \\ 0&0&0&0&\ddots \end{array} \right). $$ As for "trying to contextualize what generator matrices are actually for," this is probably a question better suited to a textbook than a math.stackexchange answer :)