Artificial Intelligence

Artificial Intelligence By Mr. Ejaz http:-owaiscomsian.wordpress.com/ CIIT Sahiwal

Artificial IntelligenceCourse outline • Introduction • Problem solving • Generic algorithms • Knowledge Representation and Reasoning • Expert Systems • Uncertainty • Learning • Planning • Advanced topics in AI CIIT Sahiwal

Artificial IntelligenceProblem Solving and Search Muhammad Ejaz CIIT Sahiwal

Problem Solving • The mechanism to find the goal performing some actions to transit from one state to another is known as problem solving. • Initial state • Operator: description of an action • State space: all states reachable from the initial state by any sequence action • Path: sequence of actions leading from one state to another • Goal test: which the agent can apply to a single state description to determine if it is a goal state • Path cost function: assign a cost to a path which the sum of the costs of the individual actions along the path. CIIT Sahiwal

Different types of problem • Well structured problems • When problem description and its rules are described clearly and unambiguously. • Ill structured problem No extra information about the problem other than the definition • No extra information • No heuristics (rules) CIIT Sahiwal

Well Defined Problems • Finding the maximum from a sequence of integers. • Eight puzzle • 1,2 or 2,1 puzzle • Farmer and goose problem • Water pouring problem CIIT Sahiwal

Eight puzzle CIIT Sahiwal

Water Pouring Problem CIIT Sahiwal

Farmer and goose problem W F ~ W F G F W F G ~ G F ~ W C W C C ~ G F G ~ C F ~ W C F ~ C F W W G ~ G G ~ G C CC F C W ~ G W CIIT Sahiwal

Think Point • What will be tree representation of Farmer and goose problem? CIIT Sahiwal

Searching For Solutions • Having formulated some problems…how do we solve them? • Search through a state space • Use a search tree that is generated with an initial state and successor functions that define the state space CIIT Sahiwal

Different search techniques • Uninformed Search Only the information available in the problem definition • Also known as blind searching -Breadth-first search -Depth-first search -Depth-limited search -Iterative deepening search • Informed Search  When sufficient information is provided to reach the goal. CIIT Sahiwal

Breadth-First Search • Recall from Data Structures the basic algorithm for a breadth-first search on a graph or tree • Expand the shallowest unexpanded node • Place all new successors at the end of a FIFO queue CIIT Sahiwal

Breadth-First Search CIIT Sahiwal

Depth-First Search • Recall from Data Structures the basic algorithm for a depth-first search on a graph or tree • Expand the deepest unexpanded node • Unexplored successors are placed on a stack until fully explored CIIT Sahiwal

Depth-First Search CIIT Sahiwal

Artificial Intelligence