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Strict link

11 replies [Last post]
daniel morais
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Joined: 2 May 2018
Posts: 20

Hi Everyone,

In my project i have some activities that can't be executed with delay, the second activity is modeled imediatly after first activity. For this reason I set "strict" on this activities.

After scheduling, the report below show me this infortmations. 

7702
scheduling_report.png

Why this happened? Why this happened with this activies and others not happened?

Best Regards,

Daniel Morais

 

 

Replies

Rafael Davila
User is online Online
Joined: 1 Mar 2004
Posts: 5050

Why Spider cannot figure it out if strict links are not mutually exclusive and there are feasible solutions.

2021-04-12-14-06-51

2021-04-12-14-16-08

Among many the following is a feasible solution.  Just delay start of activity 3.

2021-04-12-14-08-04

https://www.mediafire.com/file/1mc12f7fo3vxwte/Activities-22.003.sprj/file

https://www.mediafire.com/file/td9ac94dqhgorva/Activities-22.004.sprj/file

Marcus Possi
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Posts: 56
Hey, I haven't tested it before, but we should think about complex and high-level features, which only "spider design" and "few planners" can even understand :)   Could you share SPRJ files (opt-everage-pers)?   tks
Rafael Davila
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Do Monte Carlo know when not to use them and issue the warning? In some iterations there might be respected while in other they might not.

In the following figure strict deterministic lags are feasible but not optimistic or pesimistic, the probabilistic strict link contradict to other conditions.

2021-04-11-16-41-03

Marcus Possi
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Joined: 27 Feb 2010
Posts: 56

Indeed 

Even if they do not work for some cases, please do not eliminate them. They work for some strict sequence conditions, and they mut not be use without a "permanent medical assistance :))

Bogdan Leonte is right - you must check if they were considered at each schedulling. Trere are also warnings reports about that, if they are not considered.

 

Imagine three activities with a hard and rigid logict hat cannot be separated from each other- they should be modelled as a planning package instead of a fragnet. There will be no need og strict link or ultra hard modification in programing algorithms.  :)

 

Bogdan Leonte
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They are indeed useful, you only need to know how and when to use them.

There are many cases when strict links contradict to other conditions and yes, Spider does not always respect strict links.

We introduced them because there were customer requirements and these customers were happy because they work properly in their projects. When we found that this link property does not work for some cases we decided to eliminate it. But when we had done this many customers requested to keep it despite the problems that appear in some cases. They know that sometimes strictness will not work but still they use them and in most cases it is helpful.

So we know about the problem with the strict links but keep this feature for our customers.

daniel morais
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Joined: 2 May 2018
Posts: 20

Hi Rafael,

Why is misleading ?

Daniel Morais

daniel morais
User offline. Last seen 5 days 8 hours ago. Offline
Joined: 2 May 2018
Posts: 20

Hi Bogdan,

Perfectly understood , thank you very much.

Daniel Morais

Rafael Davila
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Posts: 5050

The label Strict Links is misleading.

Bogdan Leonte
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Hello Daniel,

When you have multiple successor for an activity you cannot have strict links. If you uncheck Use in scheduling property of link between 0108 and 4335 the strict link will be respected. For all other activities it must be a similar problem (I did not check them all).

Also you cannot have multiple successor with strict links.

Vladimir can better explain why the strict link is not respected if an activity has multiple successors.

Best regards,
Bogdan

daniel morais
User offline. Last seen 5 days 8 hours ago. Offline
Joined: 2 May 2018
Posts: 20

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