Basic Set Theory: Determining Relations: Reflexive, Symmetric, Transitive

In summary, the conversation discusses a homework problem involving relations and determining whether they are reflexive, nonreflexive, symmetric, nonsymmetric, asymmetric, antisymmetric, transitive, nontransitive, and intransitive. The given relation is concluded to be nonreflexive, nonsymmetric, and transitive, but the difference between asymmetric and antisymmetric is still being clarified.
  • #1
Bob4040
4
0
I am taking a philosophy course that covers basic set theory as part of the introduction. I’m not sure in which section of the forum set theory should be, but I think this is the right place.

Homework Statement



For each of the following relations, indicate whether it is Reflexive, Nonreflexive, Irrelfexive, Symmetric, Nonsymmetric, Asymmetric, Antisymmetric, Transitive, Nontransitive, and Intransitive.

9) {(b,d), (a,c), (d,c), (e,e), (b,c)} on the set {a,b,c,d,e}.

Homework Equations


The Attempt at a Solution



I believe they are Nonreflexive, nonsymmetric, and transitive.

I do not know if they are Asymmetric or Antisymmetric because I do not know how to deal with (e,e).
 
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  • #2
You are correct that this relation is not symmetric because it contains (a, c) but not (c, a). It is not reflexive because it does not contain (a, a), (b, b), and (c, c). It is transitive because the only pairs of the form '(x, y), (y, z)' are (b, d) and (d, c) and it does contain (b, c). What is the difference between 'asymmetric' and 'antisymmetric'?
 
  • #3
HallsofIvy said:
What is the difference between 'asymmetric' and 'antisymmetric'?


Asymmetric: [itex]xRy \Rightarrow \neg (yRx) [/itex]

Antisymmetric: [itex]xRy \wedge yRx \Rightarrow x=y [/itex]
 

1. What is the definition of a reflexive relation in basic set theory?

A reflexive relation is a relation between elements of a set where each element is related to itself. In other words, if a is related to b, then a must also be related to itself.

2. How can you determine if a relation is reflexive?

To determine if a relation is reflexive, you can check if each element in the set is related to itself. If this is true for all elements, then the relation is reflexive.

3. What is the definition of a symmetric relation in basic set theory?

A symmetric relation is a relation between elements of a set where if a is related to b, then b must also be related to a. In other words, the order of the elements in the relation does not matter.

4. How can you determine if a relation is symmetric?

To determine if a relation is symmetric, you can check if for every pair of related elements a and b, b is also related to a. If this is true for all pairs, then the relation is symmetric.

5. What is the definition of a transitive relation in basic set theory?

A transitive relation is a relation between elements of a set where if a is related to b and b is related to c, then a must also be related to c. In other words, if there is a chain of related elements, then the first and last elements must also be related.

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