هوش مصنوعی - فصل سوم

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: (goal formulation): (problem formulation): (search): ) ) . (execute): .4

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: : ( ) Arad : ( ) Bucharest : : : : Arad, Sibiu, Fagaras, Bucharest

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function SIMPLE-PROBLEM-SOLVING-AGENT(percept) return an actionstatic: seq , an action sequencestate, some description of the current world stategoal, a goalproblem, a problem formulation

state UPDATE-STATE(state, percept)if seq is empty thengoal FORMULATE-GOAL(state)problem FORMULATE-PROBLEM(state , goal)seq SEARCH(problem)action FIRST(seq)seq REST(seq)return action

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: (Single State) : (Sensorless/Conformant) : (Contingency) : (Exploration/Online)11

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: 5 ] [12

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: {21.... 8} : ] [13

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: {31} ( ) : 16

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. (initial state): Arad (successor function): (goal test): (explicit) (implicit) (path cost): C(x, a, y) . (solution): . (optimal solution) : .19

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: : 8 : :{ } : {7 8} : 20

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: 8 1) : : : : 8 : - 22

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: 8 1) ( ): : : : 8 : - 100 .23

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: 8 2) : : 8 : : : - 24

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= . . ( )28

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function SIMPLE-PROBLEM-SOLVING-AGENT(percept) return an actionstatic: seq , an action sequencestate, some description of the current world stategoal, a goalproblem, a problem formulation

state UPDATE-STATE(state, percept)if seq is empty thengoal FORMULATE-GOAL(state)problem FORMULATE-PROBLEM(state , goal)seq SEARCH(problem)action FIRST(seq)seq REST(seq)return action

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function SIMPLE-PROBLEM-SOLVING-AGENT(percept) return an actionstatic: seq , an action sequencestate, some description of the current world stategoal, a goalproblem, a problem formulation

state UPDATE-STATE(state, percept)if seq is empty thengoal FORMULATE-GOAL(state)problem FORMULATE-PROBLEM(state , goal)seq SEARCH(problem)action FIRST(seq)seq REST(seq)return action

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function TREE-SEARCH(problem, strategy) return a solution or failureInitialize search tree to the initial state of the problemdo if no candidates for expansion then return failure else choose leaf node for expansion according to strategyif node contains goal state then return solutionelse expand the node and add resulting nodes to the search treeend do

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function TREE-SEARCH(problem, strategy) return a solution or failureInitialize search tree to the initial state of the problemdo if no candidates for expansion then return failure else choose leaf node for expansion according to strategyif node contains goal state then return solutionelse expand the node and add resulting nodes to the search treeend do

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function TREE-SEARCH(problem, strategy) return a solution or failureInitialize search tree to the initial state of the problemdo if no candidates for expansion then return failureelse choose leaf node for expansion according to strategyif node contains goal state then return solutionelse expand the node and add resulting nodes to the search treeenddo .

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function TREE-SEARCH(problem, strategy) return a solution or failureInitialize search tree to the initial state of the problemdo if no candidates for expansion then return failureelse choose leaf node for expansion according to strategyif node contains goal state then return solutionelse expand the node and add resulting nodes to the search treeenddo

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function SIMPLE-PROBLEM-SOLVING-AGENT(percept) return an actionstatic: seq , an action sequencestate, some description of the current world stategoal, a goalproblem, a problem formulation

state UPDATE-STATE(state, percept)if seq is empty thengoal FORMULATE-GOAL(state)problem FORMULATE-PROBLEM(state , goal)seq SEARCH(problem)action FIRST( seq )seq REST(seq)return action

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(2)37function TREE-SEARCH(problem, fringe) return a solution or failurefringe INSERT(MAKE-NODE(INITIAL-STATE[problem]), fringe)loop doif EMPTY?(fringe) then return failurenode REMOVE-FIRST(fringe)if GOAL-TEST[node] then return SOLUTION(node)else fringe INSERT-ALL(EXPAND(node, problem), fringe)

)Remove-First ) Goal Test) Expand ) Insert_All

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function TREE-SEARCH(problem, strategy) return a solution or failureInitialize search tree to the initial state of the problemdo if no candidates for expansion then return failureelse choose leaf node for expansion according to strategyif node contains goal state then return solutionelse expand the node and add resulting nodes to the search treeenddo

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) 39

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(state) .

(node) . . (FRINGE) . ( ) 40

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41function EXPAND(node,problem) return a set of nodessuccessors the empty setfor each in SUCCESSOR-FN[problem](STATE[node]) dos a new NODESTATE[s] resultPARENT-NODE[s] nodeACTION[s] actionPATH-COST[s] PATH-COST[node] + STEP-COST(node, action,s)DEPTH[s] DEPTH[node]+1add s to successorsreturn successors

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. () . : : : / : 42

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:(b): (d): (m): ( )43

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( ).

( ).

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(Breadth-first search) (Uniform-cost search) (Depth-first search) (Depth-limited search) (Iterative deepening search) (Bidirectional search)45

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1) (fringe) FIFO

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1) FIFO

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1) FIFO

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1) FIFO

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1) FIFO

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(BF Search) : (d) . (b) .51

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(BF Search) : .52

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(BF Search) b . b . d . .

.

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1) ) 2 4

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(b=10) . . .55

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: . ( ) .

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2) . . : fringe BF .57

2) : . . : .

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2) C* . . . .

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3) . : fringe LIFO ()60

3) . : fringe LIFO ()61

3) . : fringe LIFO ()62

3) . : fringe LIFO ()63

3) . : fringe LIFO ()64

3) . : fringe LIFO ()65

3) . : fringe LIFO ()66

3) . : fringe LIFO ()67

3) . : fringe LIFO ()68

3) . : fringe LIFO ()69

3) . : fringe LIFO ()70

3) . : fringe LIFO ()71

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3) m d . BF . .

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4) DF (L) . . Ld . L=d .

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4) function DEPTH-LIMITED-SEARCH(problem,limit) return a solution or failure/cutoffreturn RECURSIVE-DLS(MAKE-NODE(INITIAL-STATE[problem]),problem,limit)

function RECURSIVE-DLS(node, problem, limit) return a solution or failure/cutoffcutoff_occurred? falseif GOAL-TEST[problem](STATE[node]) then return SOLUTION(node)else if DEPTH[node] == limit then return cutoffelse for each successor in EXPAND(node, problem) doresult RECURSIVE-DLS(successor, problem, limit)if result == cutoff then cutoff_occurred? trueelse if result failure then return resultif cutoff_occurred? then return cutoff else return failure

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5) L BF DFfunction ITERATIVE_DEEPENING_SEARCH(problem) return a solution or failureinputs: problemfor depth 0 to doresult DEPTH-LIMITED_SEARCH(problem, depth)if result cuttoff then return result

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78Limit=0

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Limit=1

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80Limit=2

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81Limit=3

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5)

level d: oncelevel d-1: 2level d-2: 3level 2: d-1level 1: dLevel 0: 1

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5) : 10 5 .

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CriterionBreadth-FirstUniform-costDepth-FirstDepth-limitedIterative deepeningBidirectional searchComplete?YES*YES*NOYES, if l dYESYES*Timebd+1bC*/ebmblbdbd/2Spacebd+1bC*/ebmblbdbd/2Optimal?YES*YES*NONOYESYES

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