Math Problem Statement

explain this:

Explain the process of finding the composition of relations R and S as shown in the example image.

Solution

The task presented in the image involves finding the composition of two relations RR and SS, denoted as SRS \circ R. Let me break it down step-by-step:


Definitions:

  1. Relation RR: A subset of {1,2,3}×{1,2,3,4}\{1, 2, 3\} \times \{1, 2, 3, 4\}, which is defined as: R={(1,1),(1,4),(2,3),(3,1),(3,4)}.R = \{(1, 1), (1, 4), (2, 3), (3, 1), (3, 4)\}.

  2. Relation SS: A subset of {1,2,3,4}×{0,1,2}\{1, 2, 3, 4\} \times \{0, 1, 2\}, which is defined as: S={(1,0),(2,0),(3,1),(3,2),(4,2)}.S = \{(1, 0), (2, 0), (3, 1), (3, 2), (4, 2)\}.

  3. Composition of Relations SRS \circ R: The composition SRS \circ R is a relation that connects an element aa from the domain of RR to an element cc in the range of SS, such that there exists an intermediate bb where: (a,b)Rand(b,c)S.(a, b) \in R \quad \text{and} \quad (b, c) \in S.

    In simpler terms, (a,c)SR(a, c) \in S \circ R if there exists some bb such that R(a,b)R(a, b) and S(b,c)S(b, c).


Step-by-Step Solution:

To compute SRS \circ R, we examine each pair in RR and check if the second element of the pair matches the first element of any pair in SS. If they match, we create a new pair where the first element is from RR, and the second element is from SS.

  1. Pairs in RR:

    • (1,1)(1, 1), (1,4)(1, 4), (2,3)(2, 3), (3,1)(3, 1), (3,4)(3, 4).
  2. Pairs in SS:

    • (1,0)(1, 0), (2,0)(2, 0), (3,1)(3, 1), (3,2)(3, 2), (4,2)(4, 2).
  3. Finding Matches:

    • For (1,1)R(1, 1) \in R: The second element is 11. Look for pairs in SS where the first element is 11. The pair (1,0)S(1, 0) \in S matches. Result: (1,0)(1, 0).
    • For (1,4)R(1, 4) \in R: The second element is 44. Look for pairs in SS where the first element is 44. The pair (4,2)S(4, 2) \in S matches. Result: (1,2)(1, 2).
    • For (2,3)R(2, 3) \in R: The second element is 33. Look for pairs in SS where the first element is 33. The pairs (3,1)(3, 1) and (3,2)S(3, 2) \in S match. Results: (2,1)(2, 1), (2,2)(2, 2).
    • For (3,1)R(3, 1) \in R: The second element is 11. Look for pairs in SS where the first element is 11. The pair (1,0)S(1, 0) \in S matches. Result: (3,0)(3, 0).
    • For (3,4)R(3, 4) \in R: The second element is 44. Look for pairs in SS where the first element is 44. The pair (4,2)S(4, 2) \in S matches. Result: (3,2)(3, 2).

Final Result:

The composition SRS \circ R is the set of pairs: SR={(1,0),(1,2),(2,1),(2,2),(3,0),(3,2)}.S \circ R = \{(1, 0), (1, 2), (2, 1), (2, 2), (3, 0), (3, 2)\}.


Explanation of the Diagram:

The diagram visually represents the relations:

  1. The nodes labeled 1,2,3,41, 2, 3, 4 and the arrows between them represent the relation RR.
  2. The nodes labeled 0,1,20, 1, 2 and their connections represent the relation SS.
  3. The combined connections (paths from RR to SS via intermediate elements) represent the composition SRS \circ R.

Do you want further clarification or details about this explanation?


5 Related Questions:

  1. What is the formal definition of a relation in set theory?
  2. How can the composition of relations be represented using matrices?
  3. Is the composition of relations SRS \circ R always commutative? Why or why not?
  4. What are some practical applications of relation composition in computer science?
  5. How can graph theory be used to visualize relation compositions effectively?

Tip:

To ensure accuracy when performing relation compositions, always systematically check every pair in RR and SS for matches, and verify intermediate elements carefully.

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Math Problem Analysis

Mathematical Concepts

Set Theory
Relations
Composition of Relations

Formulas

Composition of Relations: (a, c) ∈ S∘R if ∃b such that (a, b) ∈ R and (b, c) ∈ S.

Theorems

Properties of Relations
Definition of Relation Composition

Suitable Grade Level

Undergraduate Mathematics or Advanced High School (Grades 11-12)