A Star Search by Sam Quan

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A Star Searchby Sam Quan
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A STAR SEARCH

• Informed Search Algorithm
• Based on function f(n) g(n) h(n)
• g(n)
• Cost from the Node START to Node n
• h(n)
• Heuristic that estimates the cost from Node n to
  the Node GOAL

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IMPLEMENTATION
366 0 366
A

• h(n)
• A 366
• B 329
• C 253
• D 374
• E 366
• F 176
• G 193

118
140
75
B
C
D
447 118 329
393 140 253
449 75 374
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IMPLEMENTATION
366 0 366
A

• h(n)
• A 366
• B 329
• C 253
• D 374
• E 366
• F 176
• G 193

118
140
75
B
C
D
447 118 329
393 140 253
449 75 374
140
99
151
F
G
E
646 (140 140) 366
671 (140 151) 193
415 (140 99) 176
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Admissibility

• Underestimation
• Optimal Solution
• Using Dijkstras
• Overestimation
• Non-optimal Solution
• Using Distance Between Two Points

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Admissibility

• Example A to D
• h(n)
• A 30
• B 15
• C 20
• D 0

30 0 30
25 10 15
A
B
10
10
10
D
C
5
30 10 20
20 20 0
Should pick ACD as the most optimal path, but ABD
is chosen instead.
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Acknowledgement

• Su Wang
• Richard Ali
• Michael Lewis