The document discusses artificial intelligence problem spaces and state space representation, outlining key concepts such as defining the problem, analyzing it, and selecting appropriate problem-solving techniques. It explains uninformed (blind) and informed (heuristic) search techniques, highlighting their differences in complexity, optimality, and methods like breadth-first and A* search. Additionally, it lists various AI problems related to games, routing, layout, assembly sequencing, and task scheduling.
◊ Problem Spaces.
◊State Space.
◊ Searching Techniques.
◊ Uninformed search technique.
◊ Informed search techniques.
◊ Some AI problems.
In This Video
3.
Problem Space
Define theproblem in detail is known as problem
space. There are 4 things concerned to solve a
particular problem.
Define the problem precisely.
Analyze the problem.
Isolate and represent the task knowledge i.e.
required to solve the problem.
Selection of the best problem solving technique
and apply it. Like Tower of Hanoi, 8 puzzle games.
4.
Set ofstates and the
connections between
them to represent the
problem.
Graph is used represent
problem.
States are represented
by nodes of the graph,
and the operators by
edges between nodes.
For simplicity it is
represented as trees,
where the initial state
is the root of the tree.
State Space
5.
S:{S,A,Action(s),Result(s,a),Cost(s,a)}
Where,
S: set ofstates like start state, goal state,
etc.
A :set of actions available.
s: an individual state from S.
Action(s): action performed on s .
a: any action from set A.
Result(s, a): An intermediate state obtain
by performing a on s.
Cost(s, a):cost of executing action a on s.
branching factor, should be minimum.
State Space Search
Search Strategy
A strategyis defined by picking the order of node
expansion.
Completeness- does it always find a solution if
one exists?
Time complexity- no. of nodes generated.
Space complexity- max no. of nodes in memory.
Optimality- does it always find least cost
solution?
Time and space is measured in
‘b’ – max branching factor of search tree.
‘d’- depth of least cost solution.
‘m’ – max depth of the state space may be
(infinite)
Uninformed Search
Alsoknown as Blind search.
Problems require no domain specific knowledge.
No idea, how to obtain solution, we apply Brute
force technique (explore every possible step).
Time consuming.
Time/Space Complexity is more.
For e.g., Travelling salesman problem for 5 cities
needs (n-1)! Search.
Non polynomial method.
Provides optimal solution.
Methods: Breath first search (BFS), Depth first
search(DFS)
10.
Informed Search
• Alsoknown as Heuristic
search(estimation).
• Search with information.
• Heuristic function is used to find steps of
the solution.
• Provides quick solution.
• Less Time and space complexity.
• Does not produce optimal solution.
• Perform search in exponential time.
• Methods: A*, Heuristic DFS, Best first
search.
11.
AI PROBLEMS
• Games:WaterJug problem ,8 Queen problem, 8
Puzzle problem
• Missionaries and Cannibals ,The Monday &
Bananas problem.
• Route finding.(computer networks, airline
travel planning system)
• Layout problems (VLSI layout, furniture
layout, packaging)
• Assembly sequencing.(Assembly of electrical
motors)
• Task Scheduling.(Time tables, manufacturing)