Search and Reasoning in AI

 Search and Reasoning in Artificial Intelligence 

What is Search?

Definition

Search is the process of finding the best or correct solution from multiple possible solutions.

Simple Examples

  • Finding a file on your laptop
  • Finding the shortest route in Google Maps
  • Searching a contact on your phone
  • AI finding the best chess move

Real-Life Example

Suppose you lost your keys.

You search

  • Bedroom
  • Hall
  • Kitchen
  • Car

until you find them.

This is called Search.


2. What is Artificial Intelligence Search? 

In AI,

Search means

Finding the best possible solution by exploring different states.

Examples

  • Robot path planning
  • Google Maps
  • Chess
  • Sudoku
  • Medical Diagnosis
  • Hotel Recommendation

3. Components of Search Problem 

Every search problem has five components.

ComponentMeaningExample
Initial StateStarting pointPune
Goal StateDestinationMumbai
ActionsPossible movesLeft, Right, Straight
State SpaceAll possible pathsAll roads between Pune and Mumbai
Path CostCost of travellingDistance or Time

Example

Google Maps

Start

Pune

↓

Possible Roads

↓

Mumbai

Goal

4. State Space 

Definition

State Space is the collection of all possible states from start to goal.

Example

          Pune
         /    \
      Nashik   Satara
      /   \      |
   Mumbai  Goa   Kolhapur

AI searches among these states.


5. Search Tree 

A search tree represents all possible solutions.

Example

          A
        / | \
       B  C  D
      / \     \
     E   F     G

Root Node

Child Nodes

Goal Node


6. Types of Search 

A. Uninformed Search (Blind Search)

Definition

Search without any additional knowledge.

AI only knows

  • Start
  • Goal

Algorithms

  • Breadth First Search (BFS)
  • Depth First Search (DFS)
  • Uniform Cost Search

Example

Searching a house room by room.


B. Informed Search (Heuristic Search)

Definition

Search using extra information.

Algorithms

  • Greedy Search
  • A* Search

Example

Google Maps

Uses

  • Distance
  • Traffic
  • Estimated Time

to find the best route.


Comparison

Uninformed SearchInformed Search
No extra knowledgeUses heuristic
SlowerFaster
Explores more nodesExplores fewer nodes
Example: BFSExample: A*

7. What is Reasoning? 

Definition

Reasoning is the process of making logical decisions using available knowledge.

Example

Statement 1

All humans are mortal.

Statement 2

Ram is a human.

Conclusion

Ram is mortal.

This is reasoning.


8. Types of Reasoning 

Deductive Reasoning

General

Specific

Example

All students study.

Manisha is a student.

Therefore,

Manisha studies.


Inductive Reasoning

Specific

General

Example

Today Sun rises.

Yesterday Sun rises.

Last week Sun rises.

Therefore,

Sun rises every day.


Abductive Reasoning

Best possible explanation.

Example

Ground is wet.

Possible reasons

  • Rain
  • Water Pipe Leakage
  • Cleaning

Most likely

Rain.


Comparison

ReasoningDirectionExample
DeductiveGeneral → Specific       Mathematics
InductiveSpecific → General     Data Science
AbductiveBest Explanation      Medical Diagnosis

9. Search vs Reasoning 

SearchReasoning
Finds solution                     Makes decision
Explores statesUses logic
Used in Path FindingUsed in Expert Systems
Example: Google MapsExample: Medical Diagnosis

10. AI Applications

Search

  • Google Maps
  • Robot Navigation
  • Chess
  • Game Playing
  • Route Planning

Reasoning

  • Medical Diagnosis
  • Chatbots
  • Recommendation Systems
  • Fraud Detection
  • Legal Expert Systems

Summary

Artificial Intelligence

        │

        ▼

Search
(Finding Solution)

        │

        ▼

Reasoning
(Making Decision)

        │

        ▼

Intelligent System

Memory Trick for Students

SEARCH
↓

Find the Best Path

Google Maps

Chess

Robot Navigation

-------------------------

REASONING
↓

Think

Analyze

Decide

Medical Diagnosis

Expert Systems

ChatGPT

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