What is artificial intelligence?
The physical symbol system
•set of entities==> symbols
•All symbols/instances related in some physical way.
•Processes(creation, modification, reproduction and
Intelligence requires knowledge
2. Hard to categorize
3. Constantly changing
4. Organisation different to usage
What is an AI technique?
•Should capture generalisation
•Understood by people who provide it
•Easily modified to correct errors and reflect changes
•Overcome bulk possibilities to produce result
3 important AI techniques?
Use of knowledge
4 steps to solve a problem
•Define problem precisely
•Isolate and represent task knowledge necessary
•Choose best problem solving technique
State space representation
• Basis of AI methods
• Formal definition for problem
• Explore space trying to find path from current
state to goal state
State space problem
•Define state space (all possible configurations of relevant
•Specify initial state
•Specify goal state
•Specify set of rules that define actions
•Rules : Applicability ->Operation
Control Strategy requirements
•It should cause motion
•It should be systematic
Heuristic Knowledge incorporated
• in rules themselves
• or as a function
• Problem description
•Solution steps can be undone?
•Problem’s universe predictable?
•Good solution obvious?
•Desired solution a state or a path?
•Large amt of knowledge absolutely required to solve the
•Can computer take problem and return solution?
Issues in Search Program Design
*instead of building entire tree, programs represent trees
in rules implicitly, and generate what needs to be explored
*forward vs backward reasoning
*knowledge representation problem and frame problem
Heuristic Search techniques
1. Depth First
2. Breadth First
3. Generate and Test
• Generate solution
• Check to see if actually a solution by comparison
• If solution found quit, else repeat all steps
4. Hill Climbing
• Simple Hill Climbing
• Steepest Ascent Hill Climbing
5. Best First Search
• A* algorithm
· Use REDUCE on each immediate subgoal until there are
no more subgoals, or until REDUCE finds a subgoal that
is not satisfied.
· If REDUCE has found a subgoal that is not satisfied,
announce that the goal is not satisfied; otherwise,
announce that the goal is satisfied.
· Use REDUCE on each subgoal until REDUCE finds a
subgoal that is satisfied.
· If REDUCE has found a subgoal that is satisfied,
announce that the goal is satisfied; otherwise, announce
that the goal is not satisfied.
9.Mean Ends Analysis
To perform means-ends analysis,
· Until the goal is reached or no more procedures are
- Describe the current state, the goal state, and
the difference between the two.
- Use the difference between the current state
and goal state, possibly with the description of
the current state or goal state, to select a
- Use the promising procedure and update the
· If the goal is reached, announce success; otherwise,