open-psa / mef

The Open-PSA Model Exchange Format
https://open-psa.github.io/mef
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Precisely specify Minimal Cut Set (MCS) and Prime Implicant (PI) #25

Open rakhimov opened 7 years ago

rakhimov commented 7 years ago

This issue came up because handling of non-coherent models by some ~popular~ software packages is such a joke that it is not even funny. Seriously.

Unfortunately, the current standard does not formally specify MCS or PI.

Since it was noted in the past that tools tend to approach non-coherent models differently and produce disagreeing, inconsistent, or different results, a precise specification of MCS and PI terms would help the community with:

- cross-validation
- quality assurance
- unfounded reliance on approximations

Fortunately, Antoine Rauzy has already done the hard part of mathematically defining the notions of MCS and PI:

A. Rauzy, "Mathematical foundation of minimal cutsets," IEEE Trans. Reliab. Eng. Syst. Saf., vol. 50, no. 4, pp. 389-396, 2001

The only thing left is to translate it properly into the human language or reference these definitions in the MEF standard.

As the result of the clear specification, a non-conforming software needs to precisely state in what aspects it differs from the standard, mathematical definition; otherwise, it would be misinforming the analysts and shouldn't call the result MCS/PI (call it degenerate-MCS, if it wishes, but not MCS). In other words, this specification would be a reference point for approximations.