AI

● Dr. Ahmad aljaafreh

What is AI?

“AI” can be defined as the simulation of human intelligence on a machine, so as to make the machine efficient to identify and use the right piece of “Knowledge” at a given step of solving a problem.

A system capable of planning and executing the right task at the right time is generally called rational.

What is AI?

subject dealing with computational models that can think and act rationally.

Does rational thinking and acting include all possible characteristics of an intelligent system?learning, perception and planning.

General Problem SolvingApproaches in AI

state : status of the solution at a given step of the problem solvingProcedure.

The problem solving procedure applies an operator to a state to get thenext state.

transition to the next state, thus, is continued until the goal (desired) state isderived. Such a method of solving a problem is generally referred to as state-space approach.

Example4-puzzle problem

two operations, blank-up (BU) / blank-down (BD) and blank-left (BL) / blank-right (BR)

state-space

Algorithm for solving state-space problemsBegin1. state: = initial-state; existing-state:=state;2. While state ≠ final state doBegina. Apply operations from the set {BL, BR, BU,BD} to each state so as to generate new-states;b. If new-states ∩ the existing-states ≠ φThen doBegin state := new-states – existing-states;Existing-states := existing-states {states}∪End;End while;End.

Algorithm for solving state-space problems

trick in solving problems by the state-space Approach

1- determine the set of operators2- use it at appropriate states of the problem.

AI problems and non-AI problems. Generally, problems, for which straightforward mathematical /logical algorithms are not readily available and which can be solved byintuitive approach only, are called AI problems.Examples:water-jug problem, Travelling Salesperson, diagnosis problems, and pattern classification.

The key to AI approach is intelligent search and matching. In an intelligentsearch problem / sub-problem, given a goal (or starting) state, one has to reach that state from one or more known starting (or goal) states

how to control the generation of states?

Some of the well-known search algorithms are:a) Generate and Testb) Hill Climbingc) Heuristic Searchd) Means and Ends analysis

(1) Generate and Test Approach:

- Generation of the state-space from a known starting state (root)

- Continues expanding the reasoning space until the goal node

- After generation of each and every state, the generated node is compared with the known goal state.

- When the goal is found, the algorithm terminates.

- Does not allow filtering of states.

(2) Hill Climbing Approach:

-total cost for reaching the goal from the given starting state (f).

- While f ≤ a predefined utility value and the goal is not reached, new nodes are generated of the current node.

-in case all the neighborhood nodes (states) yield an identical value of f and the goal is not included in the set of these nodes, the search algorithm is trapped

-to overcome this problem is to select randomly a new starting state and then continue.

Example: trigonometric identities proof.

(3) Heuristic Search:

- use one or more heuristic functions to determinethe better candidate states among a set of legal states.

-The heuristic function measures the fitness of the candidate states.

(d) Means and Ends Analysis:

-attempts to reduce the gap between the current state and the goal state.

-measure the distance between the current state and the goal, and then apply an operator to the current state, so that the distance between the resulting state and the goal is reduced.

Example: mathematical theorem- proving processes.

Good general problem solving techniques in AI:

-Problem Decomposition

-Constraint Satisfaction:

evaluate the variables X1, X2 and X3 from the following set of constraints:{ X1 ≥ 2; X2 ≥3 ; X1 + X2 ≤ 6; X1 , X2 , X3 I }.∈

The Disciplines of AI

Topics which we find significant and worthwhile to understand

Learning Systems:

Knowledge Representation and Reasoning:

Knowledge Acquisition:

Intelligent Search:

Logic Programming:

Soft Computing: Fuzzy, Neural, Genetic

Applications of AI Techniques

- Expert Systems:

consists of a knowledge base, database and an inference engine

- Image Understanding and Computer Vision:

- Navigational Planning for Mobile Robots:

camera or ultrasonic sensors

static and dynamic environments

- Speech and Natural Language Understanding:

- Intelligent Control & Scheduling:

A Brief History of AI

Professor Peter Jackson of the University of Edinburgh classified the historyof AI into three periods namely i) the classical period (of game playing andtheorem proving), ii) the romantic period, and iii) the modern period the major research work carried out during these periods is presented below.

The Classical Period

This period dates back to 1950. The main research works carried out during this period include game playing and theorem proving. The concept of statespace approach for solving a problem, which is a useful tool for intelligent problem-solving even now, was originated during this period.

Turing’s “test”, which is a useful tool to test machine intelligence,originated during this period.

The Romantic Period

The romantic period started from the mid 1960s and continued until the mid1970s. During this period, people were interested in making machines“understand”, by which they usually mean the understanding of naturallanguages.

The Modern Period

The modern period starts from the latter half of the 1970s to the present day.This period is devoted to solving more complex problems of practicalinterest.