Custom Precedence Types in ALICE Pro & Core

Dependencies among operations are illustrated with precedence relationships, which indicate the order in which the operations need to be performed.

 

COMMON PRECEDENCE TYPES

The most common types of dependencies are the following four (4):

1. Finish-To-Start (FS): Activity B can begin after A is finished.

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In other words: Finish A ≤ Start B

 

2. Start-To-Start (SS): Activity B can start at the same time as A.

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In other words: Start A ≤ Start B

 

3. Finish-To-Finish (FF): Activity B can finish at the same time as A.

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In other words: Finish A ≤ Finish B

 

4. Start-To-Finish (SF): Activity B can finish at the same time as A starts.

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In other words: Start A ≤ Finish B

 

ALICE'S CUSTOM PRECEDENCE TYPES

In ALICE, the above relationship types are extended by adding the "At" type, which imposes the type of dependency. Therefore, the additional precedency types are transformed to:

1. Finish - At - Start (FaS): Activity B must begin after A is finished.

Or: Finish A = Start B

2. Start - At - Start (SaS): Activity B must start at the same time as A.

Or: Start A = Start B

3. Finish - At - Finish (FaF): Activity B must finish at the same time as A finishes.

Or: Finish A = Finish B

4. Start - At - Finish (SaF): Activity B must finish at the same time as A starts.

Or: Start A = Finish B

 

Be mindful when using the custom precedence types, as they impose a very strict relationship between activities, which can render your schedule infeasible. 

 

Further Resources

 

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