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

  • Thread starter Bob4040
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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).
 

Answers and Replies

  • #2
HallsofIvy
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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
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What is the difference between 'asymmetric' and 'antisymmetric'?

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

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

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