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Heuristic Miner empty output/input sets

edited March 2014 in Process Mining

Hi guys,

I don't understand the presence of some empty I/O sets for tasks in Causal net mined with Heuristic Miner plugin. More precisely, I expect to find such empty sets when considering start/end activities; but what does it mean when a task results to be connected to one, two tasks? For example, by exploiting the "repairExample" excercise, by filtering it (I consider a timeframe which involves just Thursday) I obtain ten instances. Mining them by setting all tresholds to 0 and with the "all task connected" option enalbed, I obtain a causal net where the task "Inform User" has as output set {{},{Repair(Complexe):complete},{Repair (Simple): complete,{Archive Repair: complete}}. What the first output means? Moreover by exploring the annotations, in the output patterns it turns out that there is a trace where "Inform Users" seems not to be followed by any other task: but I have checked the log and it is always followed by another task, it isn't an end task in any trace.

Can anyone help me? Thank you!

Best Answer

  • jribeiro
    Accepted Answer


    By the definition, an empty I/O set of a task X occurs when - in a trace - there is no task Y that can be considered as input/output of X. The evident examples are when X is a start or end task. Remark that a task can be a start/end task even though it has some inputs/outputs (e.g., in some traces the task is the start task, in some other traces it's not). 

    The inputs/outputs of a task are defined by the dependency graph; the joins/splits (i.e., I/O sets) of a task are computed by replaying the log on that dependency graph. Therefore, if some inputs or outputs of a task are missing in the dependency graph then the I/O sets may be empty. These cases usually happen when there low frequent behavior or noise in the data. Choosing the right thresholds may solve this issue.



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