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Limit XOR and IFF to two arguments #59

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rakhimov commented Jan 20, 2018

Currently, XOR and IFF are specified as n-ary connectives.
Besides being rarely used/needed,
these connectives are not intuitive in their associative, n-ary forms.
For example, a naive user may confuse XOR with natural 'either .. or',
which doesn't hold with more than 2 args;
it is rather 'odd' (pun intended :)).

I think those FTA tools that do support these gates
limit the number of arguments to 2 (e.g., graphically).
It would be unreasonable to require generality without a practical need.

Limit XOR and IFF to two arguments
Currently, XOR and IFF are specified as n-ary connectives.
In addition to being rarely used,
these connectives are not intuitive in their associative, n-ary forms.
For example, a naive user may confuse XOR with natural 'either .. or',
which doesn't hold with more than 2 args;
it is rather 'odd' (pun intended :)).

I think those FTA tools that do support these gates
limit the number of arguments to 2 (e.g., graphically).
It would be unreasonable to require generality without a practical need.

@rakhimov rakhimov added the fault-tree label Jan 20, 2018

@cfolleau

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cfolleau commented Jan 20, 2018

I agree totally. Never seen the use of un XOR with more than 2 args. Moreover there to 2 ways defined it (either one and only one, or parity)

rakhimov added a commit to rakhimov/scram that referenced this pull request Jan 23, 2018

Limit XOR & IFF to 2 arguments in schema
These connectives are not intuitive with more than 2 args.
More reasoning: open-psa/mef#59

Issue #231

rakhimov added a commit to rakhimov/scram that referenced this pull request Jan 23, 2018

Limit XOR & IFF to 2 arguments in schema
These connectives are not intuitive with more than 2 args.
More reasoning: open-psa/mef#59

Issue #232
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