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Re: what is admissible??

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  • gSm Shourov
    Admissible Heuristic: #Def : A heuristic function (h(n)) with restriction that never overestimates the path cost ( n -- G ). where n = any node/state along
    Message 1 of 3 , Oct 20, 2003
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      Admissible Heuristic:

      #Def : A heuristic function (h(n)) with restriction that never
      overestimates the path cost ('n'-->'G').
      where 'n'= any node/state along the path,
      & 'G'= desired Goal state/locaton.

      #Ex : h SLD (n) = Straight-line distance between n & goal.
      (in the route-finding problem.)

      #This is a monotonic increasing function since it follows
      the Triangle inequality
      (sum of any two sides of a triangle > the third side)
      (QED by Pearl in 1984 )

      #its a function of any kind, not an algorithm





      --- In aima-talk@yahoogroups.com, "fakarim_nsu" <fakarim_nsu@y...>
      wrote:
      > Hi there,
      > "admissible" heuristic can be any function.But provided that it
      > cannot overestimate the cost to reach the goal!for example in the 8
      > puzzle problem in the text, a rule of thumb can be it may need 20
      > moves to reach the desired goal. Now if ur heuristic takes the
      > misarranged tiles as a function or the "manhattan distance" which
      is
      > the distance for a tile from its actual position both of them can
      be
      > considered as "admissible heuristic" because none of them exceeds
      > the 20 moves(the example in the book shows they need 7 and 14 steps
      > respectively i guess).Thanx
      >
      >
      >
      > --- In aima-talk@yahoogroups.com, "hkstudentinuk"
      > <hkstudentinuk@y...> wrote:
      > > Hi there everyone
      > >
      > > I am new to AI, just starting a new couse.
      > >
      > > what is the definition of admissible?? is admissible an
      algorithem?
      > > is the definition of it "never overestimates the cost to reach
      the
      > > goal"?
      > >
      > > what does admissible means in english in this context?
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