Minds How Work
Behavior Nets
Stan Franklin
Computer Science Division & Institute for Intelligent Systems The University of Memphis
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Desired Characteristics
Goal oriented Opportunistic Persistent Able to plan ahead Robust Reactive Fast Note lack of independence Tradeoffs needed Optimality not asked for Good enough will do
February 22, 2005
HMW: Behavior Nets
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Competence Modules
Simple Interactive Mindless Each with a specific competence Like processors, codelets, demons, schema
February 22, 2005
HMW: Behavior Nets
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A Competence Module
Much like a production rule, demon, schema Preconditions environmental facts required for the competence to be performed An action Additions and deletions facts to be added or deleted after the action is taken Activation a number, some kind of strength level
February 22, 2005
HMW: Behavior Nets
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The Behavior Network
Competence module = node of a digraph links are completely determined by the competence modules
Successor links Predecessor links Conflictor links
February 22, 2005
HMW: Behavior Nets
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Successor links
Preconditions
Competence
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HMW: Behavior Nets
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Predecessor links
Preconditions
Competence
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Conflictor links
Preconditions
Competence
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Activation Comes From
Activation stored by the competence modules from the environment from built-in, global goals
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HMW: Behavior Nets
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Environmental Activation
Environment activation for each true precondition The more true preconditions, the more relevant the competence is This source of activation allows the system to be opportunistic
February 22, 2005
HMW: Behavior Nets
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Goal Activation
If a competence satisfies a goal, the goal will send activation This source of activation tends to make the system goal directed A completed goal inhibits any competence that will undo it
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Activation Along Successor Links
Activation spread from competence to competence along links Along successor links, one competence strengthens those competencies preconditions whose it can help fulfill
February 22, 2005
HMW: Behavior Nets
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Activation Along Predecessor & Conflictor Links
Along predecessor links, a competence strengthens any other that fulfills one of its own preconditions Along a conflictor link a competence inhibits any other that can undo one of its true preconditons Every conflictor link is inhibitory
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Executable Competence
Call a competence module executable if all of its preconditions are satisfied The competence is ready to fire, although it may well not
February 22, 2005
HMW: Behavior Nets
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Behavior Net Loop
Add activation from environment and goals Spread activation forward and backward among the competence modules Decay - total activation remains constant Competence fires if
it's executable and it's over threshold and it's the maximum such
If one competence fires, its activation is zero, and threshold returns to normal If none fires, reduce threshold by 10%
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Global Parameters
Activation threshold
Raising it makes the system more thoughtful, Lowering makes it more reactive
Activation added for each satisfied precondition
Increasing makes the system more opportunistic
Activation for being able to satisfy a goal
Increasing leads to more goal-oriented behavior
Last two parameters tradeoff, since goal orientation and opportunism are opposite Parameters remain constant during a run February 22, 2005 HMW: Behavior Nets
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Plans
Sequence of competencies transform present situation into desired one Sequence can become highly activated by forward spreading from c...