Arad Neamt 366 Bucharest 0 87 Zerind 151 Craiova 160 75 - - PowerPoint PPT Presentation

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Arad Neamt 366 Bucharest 0 87 Zerind 151 Craiova 160 75 - - PowerPoint PPT Presentation

Jan 08, 2024 467 likes •1.1k views

Straightline distance Oradea to Bucharest 71 Arad Neamt 366 Bucharest 0 87 Zerind 151 Craiova 160 75 Dobreta 242 Iasi Eforie Arad 161 140 92 Fagaras 178 Sibiu Fagaras 99 Giurgiu 77 118 Hirsova 151 Vaslui 80 Iasi

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Bucharest Giurgiu Urziceni Hirsova Eforie Neamt Oradea Zerind Arad Timisoara Lugoj Mehadia Dobreta Craiova Sibiu Fagaras Pitesti Rimnicu Vilcea Vaslui Iasi

Straight−line distance to Bucharest 160 242 161 77 151 241 366 193 178 253 329 80 199 244 380 226 234 374 98

Giurgiu Urziceni Hirsova Eforie Neamt Oradea Zerind Arad Timisoara Lugoj Mehadia Dobreta Craiova Sibiu Fagaras Pitesti Vaslui Iasi Rimnicu Vilcea Bucharest

71 75 118 111 70 75 120 151 140 99 80 97 101 211 138 146 85 90 98 142 92 87 86

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Arad 366

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Zerind Arad Sibiu Timisoara 253 329 374

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Rimnicu Vilcea

Zerind Arad Sibiu Arad Fagaras Oradea Timisoara 329 374 366 176 380 193

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Rimnicu Vilcea

Zerind Arad Sibiu Arad Fagaras Oradea Timisoara Sibiu Bucharest 329 374 366 380 193 253

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Arad 366=0+366

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Zerind Arad Sibiu Timisoara 447=118+329 449=75+374 393=140+253

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Zerind Arad Sibiu Arad Timisoara

Rimnicu Vilcea

Fagaras Oradea 447=118+329 449=75+374 646=280+366 413=220+193 415=239+176 671=291+380

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Zerind Arad Sibiu Arad Timisoara Fagaras Oradea 447=118+329 449=75+374 646=280+366 415=239+176

Rimnicu Vilcea

Craiova Pitesti Sibiu 526=366+160 553=300+253 417=317+100 671=291+380

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Zerind Arad Sibiu Arad Timisoara Sibiu Bucharest

Rimnicu Vilcea

Fagaras Oradea Craiova Pitesti Sibiu 447=118+329 449=75+374 646=280+366 591=338+253 450=450+0 526=366+160 553=300+253 417=317+100 671=291+380

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Zerind Arad Sibiu Arad Timisoara Sibiu Bucharest

Rimnicu Vilcea

Fagaras Oradea Craiova Pitesti Sibiu Bucharest Craiova

Rimnicu Vilcea

418=418+0 447=118+329 449=75+374 646=280+366 591=338+253 450=450+0 526=366+160 553=300+253 615=455+160 607=414+193 671=291+380

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G n G2 Start

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Next: Example Up: l3 Previous: Optimality of A*

IDA*

Series of Depth-First Searches Like Iterative Deepening Search, except use A* cost threshold instead of depth threshold Ensures optimal solution queueing-fn is enqueue-at-front if f(child) threshold Threshold is h(root) for first pass Next threshold is f(min_child), where min_child is cutoff child with minimum f value This conservative increase ensures cannot look past optimal cost solution

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Next: Eight Puzzle Example Up: l3 Previous: IDA*

Example

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Next: Eight Puzzle Example Up: l3 Previous: IDA*

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Next: Eight Puzzle Example Up: l3 Previous: IDA*

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Next: Eight Puzzle Example Up: l3 Previous: IDA*

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Next: Eight Puzzle Example Up: l3 Previous: IDA*

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Next: Eight Puzzle Example Up: l3 Previous: IDA*

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Next: Eight Puzzle Example Up: l3 Previous: IDA*

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Next: Eight Puzzle Example Up: l3 Previous: IDA*

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Next: Eight Puzzle Example Up: l3 Previous: IDA*

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Next: Eight Puzzle Example Up: l3 Previous: IDA*

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Next: Eight Puzzle Example Up: l3 Previous: IDA*

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Next: Eight Puzzle Example Up: l3 Previous: IDA*

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Next: Eight Puzzle Example Up: l3 Previous: IDA*

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Next: Eight Puzzle Example Up: l3 Previous: IDA*

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Next: Eight Puzzle Example Up: l3 Previous: IDA*

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Next: Eight Puzzle Example Up: l3 Previous: IDA*

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Next: Eight Puzzle Example Up: l3 Previous: IDA*

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Next: Eight Puzzle Example Up: l3 Previous: IDA*

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Next: Eight Puzzle Example Up: l3 Previous: IDA*

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Next: Eight Puzzle Example Up: l3 Previous: IDA*

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Next: Eight Puzzle Example Up: l3 Previous: IDA*

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Next: Eight Puzzle Example Up: l3 Previous: IDA*

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Next: Eight Puzzle Example Up: l3 Previous: IDA*

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Next: Eight Puzzle Example Up: l3 Previous: IDA*

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Next: RBFS Up: l3 Previous: Eight Puzzle Example

Analysis

Some redundant search, but small amount compared to work done on last iteration Dangerous if f values are very close If threshold = 21.1 and next value is 21.2, probably only include 1 new node each iteration Time: Space: SMA* search can be used to remember some nodes from one iteration to the next.

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n c(n,a,n’) h(n’) h(n) G n’

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2

Start State Goal State

5 1 3 4 6 7 8 5 1 2 3 4 6 7 8 5

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2

Start State Goal State

5 1 3 4 6 7 8 5 1 2 3 4 6 7 8 5

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