Logical Diagrams

Logical diagrams are graphical representations used to illustrate relationships, connections, or logical structures between various elements, concepts, or entities. They are crucial in visually presenting complex information in a simplified and understandable manner.

Types of Logical Diagrams

1. Venn Diagrams

  • Venn diagrams are widely used to illustrate the relationship between sets.
  • Each set is represented by a circle, and the overlapping areas show the elements that belong to both sets.
  • Venn diagrams are useful for understanding intersections, unions, and complements of sets.

2. Euler Diagrams

  • Euler diagrams are similar to Venn diagrams but are typically used for a broader range of relationships beyond just set theory.
  • They show relationships and connections between different groups or concepts, allowing for a more versatile representation.

3. Concept Maps

  • Concept maps display relationships between concepts or ideas in a hierarchical or networked structure.
  • Concepts are connected by labeled arrows, showing the relationships and their nature (e.g., causes, effects, is-a, part-of).

4. Flowcharts

  • Flowcharts represent a sequence of steps or processes using various symbols and arrows to indicate the flow of information, actions, or decisions.
  • They are valuable in illustrating procedures, algorithms, and decision-making processes.

5. Tree Diagrams

  • Tree diagrams display hierarchical relationships in a branching structure.
  • They are often used in decision analysis, probability theory, and family tree representations.

Key Components of Logical Diagrams

1. Shapes and Symbols

  • Different shapes and symbols represent specific elements, concepts, or actions in logical diagrams.
  • Standardized symbols help in conveying meaning and maintaining consistency.

2. Arrows and Lines

  • Arrows and lines are used to depict connections, relationships, or flow between elements or concepts.
  • The direction and style of the arrows often carry specific meanings.

3. Labels and Text

  • Labels and text are essential for providing descriptions, names, or additional information about the elements in the diagram.
  • Clear and concise labeling is crucial for understanding the diagram.

How to Create Effective Logical Diagrams

  1. Identify the Objective:

    • Clearly define the purpose and what you want to communicate through the diagram.
  2. Organize Information:

    • Arrange the elements or concepts in a logical and structured manner.
  3. Choose the Appropriate Diagram Type:

    • Select the most suitable type of logical diagram based on the relationships you want to depict.
  4. Use Consistent Symbols and Formatting:

    • Maintain uniformity in shapes, symbols, colors, and fonts to enhance readability and understanding.
  5. Label Clearly:

    • Ensure that labels and text are clear, descriptive, and relevant to convey the intended information.
  6. Consider the Audience:

    • Tailor the complexity and level of detail in the diagram according to the audience's knowledge and understanding.
  7. Review and Revise:

    • Review the diagram to ensure accuracy, clarity, and effectiveness in conveying the intended message. Make necessary revisions as needed.

Example : 

Question : Which of the following diagrams indicates the best relation between
Profit, Dividend and Bonus ?

Solution : B

Bonus and Dividend are different from each other. But both these are parts of profit. 

Question : 

In the following diagram the boys who are athletic and are disciplined are indicated by which number?

  1. 1
  2. 2
  3. 10
  4. 6

 Solution : B

Question : 

Directions to Solve

In the following figure small square represents the persons who know English, triangle to those who know Marathi, big square to those who know Telugu and circle to those who know Hindi. In the different regions of the figures from 1 to 12 are given.

How many persons can speak English and Hindi both the languages only ?
  1. 5
  2. 8
  3. 7
  4. 18

Solution : A

Number of persons who can speak English and Hindi both only is 5. 


Logical diagrams, including Venn diagrams, Euler diagrams, concept maps, flowcharts, and tree diagrams, are powerful tools for visualizing relationships, structures, and processes. Understanding their types, components, and how to create effective diagrams is essential for effective communication and analysis in various fields.