Ch. 15 Acquiring First-order Knowledge About Air Traffic Control

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Ch. 15 Acquiring First-order Knowledge About Air
Traffic Control

• Yves Kodratoff and Christel Vrain
• ??? ? ? ?

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Contents.

• Problem Domain
• Overall Learning Process
• Application of ATC

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Air Traffic Control(ATC)

• avoid the crash of an aircraft
• if collision is possible, modify the route of the
  planes

BR1667(1)
AF2470(1)
(2)
(2)
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Representation of Knowledge and Generalization

• Trade-off
• expressive power
• computational complexity
• Generalization
• By using background knowledge

BK ?x ?y owns(x,y)?car(y) ? driver(x,y) ?x
new_driver(x) ? driving_license(x) driving_licens
e(John)?owns(John, C1) ?car(C1) new_driver(Bob)?ow
ns(Bob,C2)?car(C2) ? driving_license(X)
?owns(X,C) ?car(C)
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Overall Learning Process
Determination of the Concepts

• determine the concepts to learn
• acquire background knowledge
• gather positive and negative examples
• generalize
• validate the knowledge

Concept C(x)
Positive and Negative Examples
Background Knowledge
Generalization Tool
Rules if G(x) then C(x)
Validation
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Choose the Language Representation

• choosing the basic vocabulary
• choosing the formalism, propositional or
  predicate, attribute-value representation etc.
• ex) (color_eyes, John, Brown)
• attribute(OBJECT,VALUE)
• color_eyes(John, Brown)
• value(OBJECT, ATTRIBUTE)
• brown(John, color_eyes)
• pred(OBJECT, ATTRIBUTE, VALUE)
• physical_descr(John, color_eyes, Brown)
• attribute(OBJECT, C) ? value(C)
• color_eyes(John, C) ? brown(C)

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Determine the Concepts to Learn

• The aim of this application is to learn decision
  rules used by a human controller.
• Define some actions that can be performed on
  aircraft to avoid an impending accident
• Do nothing the action is performed on the other
  aircraft
• Change of direction which is a temporary
  modification of the route
• Change of route of the aircraft
• ...
• A solution of a conflict is a combination of
  these actions

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Obtain the Examples and Rewriting Them

• Obtain the Raw Examples
• Rewrite

(? (present_work_load PWL1)(steady PWL1)
(destination AF2470 DESTINATION1)(west_european
DESTINATION1) (destination AF2470
DESTINATION2)(far_away DESTINATION2)
(solution AF2470 SOLUTION1)(change_direction
SOLUTION1) (right SOLUTION1) (solution
BR1667 SOLUTION2))
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Rewrite BK as Horn Clauses

• IF a given plan has a steady trajectory when
  entering, exiting the sector and inside the
  sector, THEN it is on cruise

?x ? y ? z ? ttraj_enter(x,y) ?
steady(y)?traj_in(x,z)?steady(z)?
traj_exit(x,t)?steady(t) ??flflight(x,fl)?cruisi
ng(fl)
?x ? y ? z ? ttraj_enter(x,y) ?
steady(y)?traj_in(x,z)?steady(z)?
traj_exit(x,t)?steady(t) ?flight(x,f(x,y,z,t) ?
x ? y ? z ? t ? fltraj_enter(x,y) ?
steady(y)?traj_in(x,z)?steady(z)?
traj_exit(x,t)?steady(t) ?flight(x,fl)
?cruising(fl)
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Generalize and Rewrite
G (?(present_work_load vg3)(steady
vg3)(destination vg1, vg21) (destination vg2
vg22)(solution vg1 vg26)(change_direction vg26)
(solution vg2 vg27)
Foreseen work load - steady Estimation of the
angle of the routes of the aircraft before
conflict occurrence - sharp convergence Solution
- vg1 change of direction...
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Conclusion

• Transformation of the examples and the experts
  knowledge in first order, and transformation of
  learning back into a representation are not
  trivial.
• The success of the learning process often relies
  on a proper choice of the formalism
• Background knowledge is often incomplete, so
  validation of learning is important.
• There is still no full automation of ATC.