Math Problem Statement

Exercise 5 Let R be the relationship on A = {2, 4, 6} and B = {♡, ♢} mentioned above. Show that R is left-total and functional.

Solution

To determine whether RR is left-total and functional, we will analyze the properties of the relation RR defined between sets A={2,4,6}A = \{2, 4, 6\} and B={,}B = \{\heartsuit, \diamondsuit\}. Let's recall what these properties mean:

  1. Left-total: For every element aAa \in A, there is at least one bBb \in B such that (a,b)R(a, b) \in R.

  2. Functional: For every aAa \in A, there is at most one bBb \in B such that (a,b)R(a, b) \in R.


Step 1: Analyze the Relation RR

Suppose RR is explicitly defined, or we infer the properties from how RR is described. Without specific pairs in RR, we assume it adheres to the properties based on a theoretical justification.


Checking Left-Total Property

  • For RR to be left-total, every element of A={2,4,6}A = \{2, 4, 6\} must be related to at least one element in B={,}B = \{\heartsuit, \diamondsuit\}.
  • This means:
    • 22 must relate to some element in BB (e.g., (2,)(2, \heartsuit)).
    • 44 must relate to some element in BB (e.g., (4,)(4, \diamondsuit)).
    • 66 must relate to some element in BB (e.g., (6,)(6, \heartsuit)).

If all elements in AA have at least one pair in RR, then RR is left-total.


Checking Functional Property

  • For RR to be functional, each element of AA must relate to exactly one element in BB, or at least at most one.
  • This means:
    • For 22, there should be exactly one pair (2,b)R(2, b) \in R with bBb \in B.
    • For 44, there should be exactly one pair (4,b)R(4, b) \in R.
    • For 66, there should be exactly one pair (6,b)R(6, b) \in R.

If no element in AA is related to more than one element in BB, then RR is functional.


Step 2: Conclusion

If RR satisfies both the above conditions, then it is left-total and functional.

Tip: To verify this fully, we need the explicit definition of RR (e.g., specific pairs). Double-check the exact set RR.


Would you like me to generate an example relation RR to confirm this analysis, or explain further details?

Expanding Questions:

  1. How is the relationship RR defined explicitly (e.g., list of pairs)?
  2. Can we represent RR as a table or diagram for clarity?
  3. Are there examples of relations that are left-total but not functional?
  4. What is the difference between functional and injective relations?
  5. How do these properties change when AA and BB have more elements?

Tip: Always represent relations graphically or as a set of ordered pairs to easily verify these properties.

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Math Problem Analysis

Mathematical Concepts

Set Theory
Relations

Formulas

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Theorems

Definitions of Left-Total and Functional Relations

Suitable Grade Level

Grades 9-12