CS460 Spring 2011

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# CS460 Spring 2011 - PowerPoint PPT Presentation

CS460 Spring 2011. Review. Overview. Course overview Propositional Logic Example CSP Example Hints for Final. Course Review. AI introduction Agents Searching Uninformed Informed Local Adversarial search Constraint satisfaction problems Propositional Logic Looking ahead.

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### CS460Spring 2011

Review

Overview
• Course overview
• Propositional Logic Example
• CSP Example
• Hints for Final
Course Review
• AI introduction
• Agents
• Searching
• Uninformed
• Informed
• Local
• Constraint satisfaction problems
• Propositional Logic
Propositional Logic Example
• 7.22 (homework problem), minesweeper

C. For each cell that has been probed, take the resulting number n revealed by the game and construct a sentence with 8 choose ndisjuncts. Conjoin all the sentences together. Then use DPLL to answer if this sentence entails X[I,j]for the I,j needed.

d. To encode the global constraint that there are M mines altogether, we can construct a disjunct with N choose M disjuncts, each of size N. For N=100 and M=20, this works out to over 10**39, which is too large for any computer. However, we can represent the global constraint within the DPLL algorithm itself, by adding min and max parameters to the DPLL function, to represent the minimum and maximum symbols that must be true in the model. For an unconstrained problem, min=0 and max=N. For the minesweeper, we can use M for both min and max. Modify DPLL to fail if min< remaining or max <0. Run DPLL recursively by subtracting 1 from both min and max when true is assigned to a symbol.

CSP Example