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Selector-Selector Conflict Across Parameter Blocks

Only selectors are able to have conflict with agents whose targets are in other parameter blocks. These conflicts are among the most widely studied in the conflict resolution and constraint satisfaction literature. This example shows how they can be handled in the SiFA paradigm.

Here the stem radius selector with strength point of view and the stem length selector with stability point of view are in conflict, as these two values are related in some way through a constraint in at least one of the agents` knowledge bases.

  
Figure 7.4: Value-value incompatibility across parameter blocks

The stem length selector sets the value of the stem length to a default value. At some point later in the design, the stem radius selector produces the value of the stem radius using the value of the stem length and the formula . The stem radius selector realizes that the value it produced violates one of its constraints, namely, Therefore it initiates a conflict. When the stem length selector produces an alternative, the stem radius selector is able to produce a value which satisfies all constraints it knows about, and the conflict is resolved.

Here is the excerpt:

Stem Length Stability Selector: Set stem length to default value
of 4 cm.

Stem Radius Strength Selector: Set stem radius value to 0.4 cm.

Stem Radius Strength Selector: Conflict detected with Stem Length
Stability Selector.

Stem Radius Strength Selector: Ask Stem Length Stability Selector
for an alternative value.

Stem Length Stability Selector: Using alternative value.

Stem Length Stability Selector: Redesigned stem length value to 
3 cm.

Stem Radius Strength Selector: Conflict with Stem Length
Stability Selector resolved.

Stem Radius Strength Selector: Redesigned stem radius value to
0.3 cm.


Ilan Berker
Thu Apr 27 16:25:38 EDT 1995