Bounds for simulation

This note is concerned with stochastic product line structures. It aims to promote that and how an analytic approach, known in the literature, can also be fruitful for the simulation of such structures. This approach is based on the modification of the system of interest so as to meet simple in=out principles. These principles, which can be checked at intuitive basis, will guarantee simple analytic, so-called product form, expressions for the steady state distribution. These, in turn, will generally lead to performance (eg delay, throughput or loss probability) bounds. The approach can be useful for the simulation of these structures such as for:
* numerical purposes (orders and bounds);
* testing (verification/validation) and
* insights (robustness/optimization).