Ex3.3: transition relation semantics (HRU model)

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felicis
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Ex3.3: transition relation semantics (HRU model)

Beitrag von felicis » 9. Mai 2016 13:17

Hi,

I would like to use the constraint for conditional requests (slide 21) for exercise part a). It would help me very much if the "implies" would be a "is equivalent to". Is this valid, or do I allow wrong semantics for the requests if I make this change?

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felicis

Markus Tasch
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Re: Ex3.3: transition relation semantics (HRU model)

Beitrag von Markus Tasch » 9. Mai 2016 15:28

As usual with formal semantics, they have to be used as they are defined. Therefore, stick to "implies" instead of "if and only if". Potentially your problem in solving Exercise 3.3a) is solved by taking another look at the definition on Slide 25 (Module 04).
Markus Tasch, M.Sc.
Modeling and Analysis of Information Systems
Department of Computer Science, TU Darmstadt
http://www.mais.informatik.tu-darmstadt.de

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Re: Ex3.3: transition relation semantics (HRU model)

Beitrag von felicis » 9. Mai 2016 22:35

Doesn't the Definition on slide 4.25 imply the equivalence?
If the transition relation is the greatest set of (single) transitions, which comply with all constraints, there cannot be any single transition which complies with the constraints, but is not present in the transition relation, can't there?
Can I just add this to my proofs? Otherwise I would have to completely rebuild my proof structure.....

best
felicis

EDIT: typo

Markus Tasch
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Re: Ex3.3: transition relation semantics (HRU model)

Beitrag von Markus Tasch » 10. Mai 2016 09:23

Doesn't the Definition on slide 4.25 imply the equivalence?
Yes, you can prove the equivalence based on definition on slide 4.25. Nevertheless, you would have to prove a corrsponding theorem to use this result in a formal proof in a clean fashion.

For Exercise 3.3:
Here a convincing argument using the formal definitions is enough because Exercise 3.3 does not ask for a formal proof.
Markus Tasch, M.Sc.
Modeling and Analysis of Information Systems
Department of Computer Science, TU Darmstadt
http://www.mais.informatik.tu-darmstadt.de

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