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I want to duplicate a use case on a diagram to make it easier to look at.
Below is the example. Actor F can do use case C and E.
So I duplicated the C use case so I don't cross actor B's association.

enter image description here

Geert Bellekens
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Andika Romansyah
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2 Answers2

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Basically this is not forbidden. Even OMG is using the same element more than once on a diagram, but only in very rare cases with generalization.

However, this is not recommended since you can not see that both bubbles are actually the same element. Further a use case diagram should bring things to the point and not look like spider webs. A clear indication that you should think over your design. If you have too many use cases it's more likely your synthesis went wrong rather than your system is really that complex.

P.S. As always I recommend reading Bittner/Spence about use cases.

qwerty_so
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  • thank you for your answer... i think i found in Bittner/Spence about use case.... page 198 https://books.google.co.id/books?id=zvxfXvEcQjUC&printsec=frontcover&source=gbs_atb#v=snippet&q=same%20element&f=false – Andika Romansyah Jan 28 '19 at 07:17
  • It's a bit more than page 198. It's about the whole use case synthesis which is important. – qwerty_so Jan 28 '19 at 09:03
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To show two times a given UC in a diagram is allowed, but not recommended for readability reason when it is useless, and in your case this is useless :

enter image description here

As Thomas says in the other answer that complexity may indicate a problem

  • are all these UCs real UC or you already think about the implementation ?
  • may be some actors can be merged ? An actor is a role
  • are all these UCs part of the same subject ? If not use several diagrams
bruno
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  • well i have about different 14 usecase and 3 actor. it's really hard to arrange it without get many crossing line... – Andika Romansyah Jan 28 '19 at 08:35
  • @AndikaRomansyah Why would you put 14 use cases on a single diagram? I would think 5 or 6 use cases per diagram should be enough. Certainly not more then 10. – Geert Bellekens Jan 28 '19 at 11:59