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Artificial Intelligence and Soft Computing: Behavioral ... - Arteimi.info

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the formation of the FPN. One point that needs special mention at this stage<br />

is clarified as follows. Let us assume that the initial fuzzy belief for the<br />

<strong>info</strong>rmation loved (ram, sita) is 0.001, i.e., very small. Under this<br />

circumstance, it is not unjustified to assume that not-loved (ram, sita) is<br />

true. However, we cannot ignore loved (ram, sita), since it is present in the<br />

database. So, because of uncertainty of the <strong>info</strong>rmation loved (ram, sita), the<br />

pair of inconsistent <strong>info</strong>rmation d1 <strong>and</strong> d6, defined below, both appear in the<br />

FPN of fig. 23.11. In fig. 23.11, d1 ,d2 ,d3 ,d4 ,d5 <strong>and</strong> d6 represent loved (ram,<br />

sita), loved (madhu, sita), tortured (ram, sita), loses-social-recognition(sita),<br />

suicides (sita) <strong>and</strong> not-loved (ram, sita) respectively.<br />

23.5.7 Algorithm for Non-monotonic Reasoning in a FPN<br />

Irrespective of the type of inconsistency, the following algorithm for nonmonotonic<br />

reasoning may be used for continuing reasoning in the presence of<br />

contradictory evidences in an FPN [10].<br />

Procedure non-monotonic reasoning (FPN, contradictory pairs)<br />

Begin<br />

i) Open the output arcs of all the contradictory pair of <strong>info</strong>rmation;<br />

ii) Check the existence of limit cycles by invoking procedures for<br />

limitcycle detection; If limitcycles are detected, eliminate limitcycles, if<br />

possible; If not possible report that inconsistency cannot be eliminated<br />

<strong>and</strong> exit;<br />

iii) Find the steady-state fuzzy beliefs of each place by invoking the<br />

steps of belief-revision procedure;<br />

iv) For each pair of contradictory evidences do<br />

Begin<br />

Set the fuzzy belief of the place having smaller steady- state belief<br />

value to zero permanently, hereafter called grounding ;<br />

If the steady-state fuzzy belief of both the contradictory pair of places is<br />

equal, Then both of these are grounded;<br />

End For;<br />

v) Connect the output arcs of the places which are opened in step (i) <strong>and</strong><br />

replace the current fuzzy beliefs by the original beliefs at all places,<br />

excluding the grounded places;<br />

vi) Open the output arcs of transitions leading to grounded places;<br />

//This ensures that grounded places are not disturbed.//<br />

End.<br />

23.5.8 Decision Making <strong>and</strong> Explanation Tracing<br />

After execution of the non-monotonic reasoning procedure, the limit-cycledetection<br />

<strong>and</strong> elimination modules are invoked for reaching an equilibrium<br />

condition in the FPN. The decision-making <strong>and</strong> explanation-tracing module

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