18CSC305J - Artificial Intelligence UNIT 1

 12M:

Explain the types of intelligent agents.

Agent:

  • An agent is anything is anything that can be viewed as perceiving its environment through sensors and acting upon the environment through actuators

Agent Program:

  • Agent’s behavior is mathematically described by an agent function

  • Agent’s behavior is practically described by an agent program

  • It is the real implementation

  • AI designs the agent program

  • To design an agent program, we need to understand

  • Percepts

  • Actions

  • Goals

  • Environment 

Types:

  • Simple reflex agents

  • Model based reflex agents

  • Goal based agents

  • Utility based agents


Simple reflex agents:

  • Uses just condition action rules

  • Works only if the environment is fully observable


Model based reflex agents:

  • For the world that is partially observable

  • The agent has to keep track of an internal state that depends on the percept history


Goal based agents:

  • Current state of the environment is always not enough

  • The goal is to achieve correctness


Utility based agents:

  • Goals alone are not enough to generate high quality behavior

  • If goal means success, utility means the degree of success



Problem Solving: 

Problem solving process:

Components of problems:

  • A problem can be defined formally by 5 components:

  • Initial state

  • actions/ operators

  • Transition model

  • A goal test

  • Path cost

Problem formulation:

  • Choosing relevant set of states and feasible set of operators for moving from one state to another

Toy world problem:

  • Intended to illustrate various problem solving methods

Real world problems:

  • One whose solutions people actually care about

Problem types:

  • Deterministic or observable

  • Non observable

  • Non deterministic or partially observable

  • Unknown state space

Example: (Toy world problem)

4-Queens: 

Given a 4 x 4 chessboard, we have to place 4 queens such that no two queens attack each other



4M:


What is an agent? / What is an agent program?


Agent:

  • An agent is anything is anything that can be viewed as perceiving its environment through sensors and acting upon the environment through actuators

Agent Program:

  • Agent’s behavior is mathematically described by an agent function

  • Agent’s behavior is practically described by an agent program

  • It is the real implementation

  • AI designs the agent program

  • To design an agent program, we need to understand

  • Percepts

  • Actions

  • Goals

  • Environment 



What is meant by a cognitive model?

  • The goal is to make systems think like humans

  • Simulating human problem solving and mental processing in a computerized model

  • It is used in various AI applications like NLP, robotics, VR, neural networks



Give complete solutions to 4 Queens problem

  • The aim of the n queens problem is to place n queens in a chessboard in such a way that no queens can attack each other ( no two queens are placed diagonally, vertically or horizontally)



What are the important AI techniques?

  • AI technique is a method that achieves knowledge.

  • The main AI techniques are

  • Search

  • Use of knowledge

  • Abstraction 

  • A search program finds solution for a problem by trying various sequences of actions until a solution is found (best way but not always possible because of large state space)

  • The use of knowledge provides a way of solving complicated problems by manipulating the structures of the objects that are concerned

  • Abstraction finds a way of separating important features and notifications from the unimportant ones that would otherwise confuse any process



Types of constraints in a CSP problem

  • CSP is a special class of search problems

  • The goal test is a set of constraints

  • Types of constraints:

  • Unary constraints: involve a single variable (Eg: SA != green)

  • Binary constraints: involve pairs of variables (Eg: SA != WA)

  • Higher order constraints: involve 3 or more variables (Eg: O + O = R + 10 . X1)

  • Preferences (soft constraints): gives constrained optimization problems (Eg: red is better than green)



What are the various constraint satisfaction problems?

  • Finding a solution that meets a set of constraints is the goal of constraint satisfaction problems

  • There are mainly 3 basic components of a CSP:

  • Variables

  • Domains

  • Constraints 

  • CSP can be categorized according to the type of domain:

  • Finite: finite domains have a finite number of possible values such as colors or integers

  • Infinite: infinite domains have a infinite number of possible values such as real numbers

  • Continuous: continuous domains have a infinite number of possible values but can be represented by a finite set of parameters

  • Examples:

  • Cryptarithmetic puzzles

  • Map coloring problems

  • Sudoku

  • crosswords



Give PEAS description for online bus reservation system

PEAS stands for 

  • Performance measures

  • Environment

  • Actuators 

  • Sensors 

Performance measures: 

  • Response time

  • Accuracy

  • User satisfaction

Environment:

  • Users

  • Bus routes

  • Payment gateways

Actuators: 

  • Seat reservation

  • Cancellation

  • Payment processing

Sensors:

  • Seat availability sensors

  • Payment status sensors



Describe various AI models


What are the characteristics of intelligent agents?

  • An agent is anything that can be viewed as perceiving its environment through sensors and acting upon that environment through actuators

  • Common characteristics of intelligent agents are adaptation based on experience, real-time problem-solving, analysis of error or success rates, and the use of memory-based storage and retrieval.

  • Human agent: eyes, ears, and other organs for sensors; hands,legs, mouth, and other body parts for actuators

  • Robotic agent: cameras and infrared range finders for sensors; various motors for actuators



What are problem solving agents?

  • A simple problem solving agent first 

  • formulates a goal and a problem

  • Searches for a sequence of actions that would solve the problem

  • Then execute the actions one at a time

  • When this is complete, it formulates another goal and starts over



What are the problems in simple reflex agents?

  • They cannot compute complex equations or solve complicated problems. 

  • They work only in environments that are fully-observable in the current percept, ignoring any percept history.



What are the conceptual components of a Learning agent?    

Four conceptual components

  • Learning element - Making improvement

  • Performance element - Selecting external actions

  • Critic - Tells the Learning element how well the agent is doing with respect to fixed performance standards. (Feedback from users or examples, good or not?)

  • Problem generator - Suggest actions that will lead to new and informative experiences.



What are the parameters of   Measuring problem-solving performance?


  • the search cost--how long the agent takes to come up with the solution to the problem, and

  • the path cost--how expensive the actions in the solution are.

The total cost of the solution is the sum of the above two quantities.


  • Completeness: Is the algorithm guaranteed to find  a solution when there is one?

  • Optimality: Does the strategy find the optimal  solution (i.e., lowest path cost among all solutions)

  • Time complexity: How long does it take to find a  solution?

  • Space complexity: How much memory is needed  to perform the search?



Define heuristic function

  • Backtracking allows to go to the previous decision-making  node to eliminate the invalid search space with respect to  constraints

  • Heuristics plays a very important role here

  • If we are in position to determine which variables should be  assigned next, then backtracking can be improved

  • Heuristics help in deciding the initial state as well as  subsequent selected states

  • Selection of a variable with minimum number of possible  values can help in simplifying the search

  • This is called as Minimum Remaining Values Heuristic (MRV)  or Most Constraint Variable Heuristic



Data acquisition:

  • There are 2 things that AI needs code and training data

  • The more accurate the training data, the more powerful the tool



What are rational agents?

  • Ideal Rational agents are ones that are capable of doing expected actions to maximize its performance measure

  • Rationality of an agent depends on

  • Performance measure

  • Percept sequence 

  • Knowledge about environment

  • Action able to be performed

  • The problem can be categorized by PEAS


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