[aadl]: Question about error model events distribution

[Denis Buzdalov]

Dear all,

We have a question related to the events occurrence distribution
setting in the EMV2.

We are talking about events occurrence and that's why the sample space
of a probability space is a set of two elements, let's designate them as
"OCCURED" and "NOT_OCCURED".

If we are talking about fixed distribution defined on this sample
space, everything is OK -- the only probability parameter (let's call
it 'p') means that the probability mass of the event "OCCURED" is 'p'
and the probability mass of the event "NOT_OCCURED" is '1 - p'.

The occurrence distribution property in EMV2 allows to set difference
probability distributions, not only the "fixed". One of possible
variants is the Poisson distribution.

The Poisson distribution can be used only with sample space of the set
of natural numbers (i.e. the Poisson distribution say the probability
of occurrence of some natural number). But events, as I said before, use
the sample space containing only two values ("OCCURED", "NOT_OCCURED").
That's why we have a conflict.

So, the question is what is the meaning of occurrence distribution
property setting applied to some event in case when the distribution is
set to Poisson? What are probabilities of "OCCURED" and "NOT_OCCURED"
sample space elements in this case?

--
Denis Buzdalov, Sergey Zelenov
Software Engineering Department, ISPRAS