Piotr Szwed

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====== Projects ======

===== Fuzzy Semantic Petri Nets =====

Fuzzy Semantic Petri Nets (FSPN) are Petri nets coupled with an underlying fuzzy ontology.

  *The fuzzy ontology stores facts about a development of a certain complex event (or a process). They are expressed as fuzzy unary or binary relations between participating objects. The ontology ABox is updated with new observations.
  *The Petri net defines a scenario of an event (or a process, if you like), its places correspond to the scenario steps
  *Tokens in FSPN represent combinations of objects participating in the event. They are attributed with weights expressing likelihood of a scenario step occurrence
  *Guards in FSPN are conjunctions of fuzzy predicates referencing the assertions in the coupled ontology  

FSPN were applied to the problem of video event recognition. In the presented example an abandonned laguagge is correctly detected. (The event scenario and the dataset were published at [[http://www.cvg.rdg.ac.uk/PETS2006/|PETS 2006 Workshop]]) . 

Scenario:
  -A man ''x'' enters the scene and is still for some time
  -Then he takes his rucksack ''y'' off and puts it on the floor. He stays close to it for some time. The rucksack should not move ''isStill(y)''.
  -Next, he leaves the rucksack unattended (the object is classified //unattended// if the distance between it and its owner is greater than 3 m). The luggage should remain still.
  -Finally, the man disappears and the luggage rest still and unattended (possible bomb planting) 

The listed above steps correspond to the places of FSPN specifying the scenario. Transition guards define the conditions that should be satisfied to reach the next step. 

{{:projects:pets-scenario.png?600}}


The clip below shows the GUI of a software, that internally usess the FSPN approach to recognize video events.  

<html>
<iframe width="560" height="315" src="//www.youtube.com/embed/_hArl9i20TY" frameborder="0" allowfullscreen></iframe>
</html>
Piotr Szwed

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