Continuous-time and continuous-space process algebras

Quantitative methods seek to explore how a system evolves in the dimensions of space and time. The usual notion of space is a discrete one such as the reachable states of a high-level model, but others are possible, such as fluid models. The usual notion of time is a continuous one such as the average duration of activities, as used in stochastic processes governed by the exponential distribution. Alternative models for the time domain include a discrete “clock ticks” model as used in synchronous process algebras. Taking only the split between continuous and discrete, and space and time, one can fashion four classes of process algebras.