AlphaBeta Home Page



Researchers in game playing have developed a class of search techniques called alpha-beta pruning to improve the efficiency of search in two person games. The idea for alpha-beta search is simple:-

  1. Alpha-beta search proceeds in a depth-first fashion rather than searching the entire space to the ply depth.
  2. Two values, called alpha and beta, are created during the search.
  3. The alpha value, associated with MAX nodes, can never decrease, and the beta value, associated with MIN nodes can never increase.

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Description on how the alpha-beta search works:

Suppose a Max node's alpha value is 6. Then MAX need not consider any backed up value less than or equal to 6 that is associated with any MIN node below it. Alpha is the worst that MAX can score given that MIN will do its best. Similarily, if MIN has a beta value of 6, it need not consider any MAX node below it that has a value of 6 or more.

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Animated version of Blocks World:
This image represents the overview of the animated version of alhabeta search.

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Static version of Aphabeta search:
This image represents the state of the static version of alphabeta search

  • alpha.html : Use this link to view the alpha-beta search


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