I.BEST FIRST SEARCH IN AI

I.BEST FIRST SEARCH IN AI

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  Topic To BeCovered: I.BEST FIRST SEARCH IN AI Jagdamba Education Society's SND College of Engineering & Research Centre Department of Computer Engineering SUBJECT: Artificial Intelligence & Robotics Lecture No-09(I) Prof.Dhakane Vikas N
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  BEST FIRST SEARCH(BFS) This is informed search technique(Greedy Search) also called as HEURISTIC search.  This algo. Works using heuristic value.  This algorithm uses evaluation function to decide which adjacent node is most promising and then explore.  Priority queue is used to store cost of function.  Space & Time Complexity of BFS is also O(V+E) where V is vertices and E is edges.  Also Written as:-O(b) ^d Where, b->Branching factor d->depth
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  BEST FIRST SEARCH(BFS) The implementation of Best First Search Algorithm involves maintaining two lists- OPEN and CLOSED.  OPEN contains those nodes that have been evaluated by the heuristic function but have not been expanded into successors yet.  CLOSED contains those nodes that have already been visited.
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  BEST FIRST SEARCH(BFS) Algorithm Priority queue ‘PQ’ containing initial states Loop  If PQ=Empty Return Fail Else  Insert Node into PQ(Open-List)  Remove First(PQ) ->NODE(Close- List)<  If NODE=GOAL  Return path from initial state to NODE ELSE  Generate all successor of NODE and insert newly generated NODE into ‘PQ’ according to cost value. END LOOP
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  BEST FIRST SEARCH(BFS) Advantagesof BFS: Memory efficient as compared with DFS & BFS It is Complete Disadvantages of BFS: It gives good solution but not optimal solution. In worst case it may behave like unguided DFS