Author Topic: Can a requirement satisfy a requirement? (SysML)  (Read 1418 times)


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Can a requirement satisfy a requirement? (SysML)
« on: November 15, 2021, 11:12:41 pm »

We have different requirement sources, some of the requirements overlap.

Any model element can satisfy a requirement. Can I therefore make the conclusion that also requirements can satisfy a requirement?

We want to indicate that, if we fulfill requirement A from one source, we also fulfill requirement B and C from other sources because of the overlap.

Or should this be modelled diffently? The copy-relationship? But it's not a copy.

Thank you!
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Re: Can a requirement satisfy a requirement? (SysML)
« Reply #1 on: November 15, 2021, 11:40:33 pm »
No, a requirement can never satisfy anything. Else it would not be a requirement. However, you can compose requirements in order to show some break down of complex requirements. It's one way to show it, though I rather have requirements not be composed. They should trace to the customer specs where they come from and be singular. The brace around should always be the customer spec. So in the end you should have decomposed that into a lot of single non-contradictory requirements which you then start to synthesize in use cases. Quite a complex process with lots of places to fail.



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Re: Can a requirement satisfy a requirement? (SysML)
« Reply #2 on: November 16, 2021, 03:25:32 am »
I would not go that far to say that requirements never satisfy other requirements, but it is very uncommon.

The relation information you want to model between your requirements is not supported by SysML.

However e.g. , the Goals in the KAOS framework defines a kind of “contribute” relationship which can be rated between -3 …+3. So you could express that fulfilling one requirement contributes a bit (+1) or very much (+3) in fulfilling another requirement. Or you could model that fulfilling one requirements makes it really hard (-3) to fulfill another requirement.
UML and SysML allows you to add something like that by a profil. So if this information is important to you, create your own profile maybe with ratings [impossible, -3, -2, -1, +1, +2, +3, entirely].
Best regards,

Peter Heintz