Efficient CSP Z Data Abstraction

Compositional abstraction of CSP Z processes

“…Data abstraction [8,16,18,21] is a powerful statespace compression technique, suitable for systems that manipulate data. It allows one to calculate simpler models that preserve desirable properties and are analysable via model checking.…”

“…Intuitively, the values 0 and 1 would be sufficient to preserve this observable behaviour. The approach proposed in [8,16] assures this by using model checking and theorem proving; it expands the process and checks if a repeated trace is infinitely allowed by the CSP part via model checking, and by the Z part via theorem proving. For example, the trace tick, tack is allowed by the CSP part because it performs any sequence of tick's and tack's.…”

“…If this same variable were involved in communications, the approach of [8,16] could not be applied. In the next section we show an example that belongs to this class of problems.…”

“…: Message is not specified and can be any value of type Message. This naturally originates state explosion that cannot be handled by any existing approach for CSP Z , including [8,16]. Fortunately, as the behaviour of Telemetry is not affected by the type Message, we can determine a minimum subset of it that is relevant to capture the behaviour of the system.…”

“…The language yields infinite state-space systems very naturally because infinite domains are allowed as types of state and communication variables. In the first situation, the infiniteness is already handled by the data abstraction approach reported in [8,16]. However, the infiniteness occurring in communications is still an open problem.…”