CS482/682 Artificial Intelligence Lecture 8: Constraint Satisfaction Problems and Logic-based...
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Transcript of CS482/682 Artificial Intelligence Lecture 8: Constraint Satisfaction Problems and Logic-based...
![Page 1: CS482/682 Artificial Intelligence Lecture 8: Constraint Satisfaction Problems and Logic-based Inference 17 September 2009 Instructor: Kostas Bekris Computer.](https://reader036.fdocuments.in/reader036/viewer/2022081603/56649e525503460f94b48699/html5/thumbnails/1.jpg)
CS482/682Artificial Intelligence
Lecture 8:Constraint Satisfaction Problems
and Logic-based Inference
17 September 2009Instructor: Kostas Bekris
Computer Science & Engineering, University of Nevada, Reno
![Page 2: CS482/682 Artificial Intelligence Lecture 8: Constraint Satisfaction Problems and Logic-based Inference 17 September 2009 Instructor: Kostas Bekris Computer.](https://reader036.fdocuments.in/reader036/viewer/2022081603/56649e525503460f94b48699/html5/thumbnails/2.jpg)
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Search-based Problems
Search ProblemsGiven the state-space, a start state and a successor functionFind a goal state
Local Search Classical Search
• Hill-climbing• Hill-climbing with random restarts• Simulated Annealing• Local Beam Search• Genetic Algorithms
Uninformed• BFS • Uniform-First• DFS• Iterat.-Deep. DFS• Bidirectional
Informed
Best-First Search• Greedy BestFS• A*
Constraint Satisfaction Problems
![Page 3: CS482/682 Artificial Intelligence Lecture 8: Constraint Satisfaction Problems and Logic-based Inference 17 September 2009 Instructor: Kostas Bekris Computer.](https://reader036.fdocuments.in/reader036/viewer/2022081603/56649e525503460f94b48699/html5/thumbnails/3.jpg)
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Constraint-Satisfaction Problems
Discrete and Finite Domains
•Map-Coloring
•8-queens puzzle
Boolean CSPs
•Satisfiability problems (prototypical NP-Complete problem)
Discrete and Infinite Domains
•Scheduling over the set of integers (e.g., all the days after today)
Continuous Domains
•Scheduling over continuous time
•Linear Programming problems
- Constraints are linear inequalities over the variables
Additional examples:
crossword puzzles, cryptography problems, Sudoku
and many classical NP-Complete problems:
•clique problems, vertex-cover, traveling salesman, subset-sum, hamiltonian-cycle
![Page 4: CS482/682 Artificial Intelligence Lecture 8: Constraint Satisfaction Problems and Logic-based Inference 17 September 2009 Instructor: Kostas Bekris Computer.](https://reader036.fdocuments.in/reader036/viewer/2022081603/56649e525503460f94b48699/html5/thumbnails/4.jpg)
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Constraint Satisfaction Problem Example
![Page 5: CS482/682 Artificial Intelligence Lecture 8: Constraint Satisfaction Problems and Logic-based Inference 17 September 2009 Instructor: Kostas Bekris Computer.](https://reader036.fdocuments.in/reader036/viewer/2022081603/56649e525503460f94b48699/html5/thumbnails/5.jpg)
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1. Backtracking Search
![Page 6: CS482/682 Artificial Intelligence Lecture 8: Constraint Satisfaction Problems and Logic-based Inference 17 September 2009 Instructor: Kostas Bekris Computer.](https://reader036.fdocuments.in/reader036/viewer/2022081603/56649e525503460f94b48699/html5/thumbnails/6.jpg)
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2. Local Search
![Page 7: CS482/682 Artificial Intelligence Lecture 8: Constraint Satisfaction Problems and Logic-based Inference 17 September 2009 Instructor: Kostas Bekris Computer.](https://reader036.fdocuments.in/reader036/viewer/2022081603/56649e525503460f94b48699/html5/thumbnails/7.jpg)
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1. Backtracking: Forward Checking
WA NT Q NSW V SA T
Initially RGB RGB RGB RGB RGB RGB RGB
After WA=R R G B RGB RGB RGB G B RGB
After Q = G R B G R B RGB B RGB
After V=B R B G R B RGB
![Page 8: CS482/682 Artificial Intelligence Lecture 8: Constraint Satisfaction Problems and Logic-based Inference 17 September 2009 Instructor: Kostas Bekris Computer.](https://reader036.fdocuments.in/reader036/viewer/2022081603/56649e525503460f94b48699/html5/thumbnails/8.jpg)
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1. Backtracking: Intelligent Backjumping
Assume WA=red and NSW =red, then assign T, NT, Q, SA
SA will cause a conflict, whatever we do...• Where should the algorithm backjump?
![Page 9: CS482/682 Artificial Intelligence Lecture 8: Constraint Satisfaction Problems and Logic-based Inference 17 September 2009 Instructor: Kostas Bekris Computer.](https://reader036.fdocuments.in/reader036/viewer/2022081603/56649e525503460f94b48699/html5/thumbnails/9.jpg)
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Wumpus World
![Page 10: CS482/682 Artificial Intelligence Lecture 8: Constraint Satisfaction Problems and Logic-based Inference 17 September 2009 Instructor: Kostas Bekris Computer.](https://reader036.fdocuments.in/reader036/viewer/2022081603/56649e525503460f94b48699/html5/thumbnails/10.jpg)
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Wumpus World
![Page 11: CS482/682 Artificial Intelligence Lecture 8: Constraint Satisfaction Problems and Logic-based Inference 17 September 2009 Instructor: Kostas Bekris Computer.](https://reader036.fdocuments.in/reader036/viewer/2022081603/56649e525503460f94b48699/html5/thumbnails/11.jpg)
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Wumpus World
![Page 12: CS482/682 Artificial Intelligence Lecture 8: Constraint Satisfaction Problems and Logic-based Inference 17 September 2009 Instructor: Kostas Bekris Computer.](https://reader036.fdocuments.in/reader036/viewer/2022081603/56649e525503460f94b48699/html5/thumbnails/12.jpg)
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Wumpus World