Equivalence Relations in Set Theory: Homework Statement and Solutions

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SUMMARY

An equivalence relation on a set A is defined by three properties: reflexivity (a~a), symmetry (a~b implies b~a), and transitivity (a~b and b~c implies a~c). In the discussion, the user references the book "Topics in Algebra, 1st Edition" by Herstein while attempting to understand how to prove these properties. The example provided, A = {1, 2, 3} with the relation {(1, 1), (1, 2), (2, 1), (2, 2)}, illustrates the concept of equivalence classes, although the user expresses confusion regarding the relationship between elements 1 and 2.

PREREQUISITES
  • Understanding of set theory concepts
  • Familiarity with equivalence relations
  • Basic knowledge of proof techniques in mathematics
  • Experience with algebraic structures as discussed in "Topics in Algebra, 1st Edition" by Herstein
NEXT STEPS
  • Study the properties of equivalence relations in detail
  • Learn how to construct proofs for mathematical statements
  • Explore equivalence classes and their applications in set theory
  • Review examples of equivalence relations in various mathematical contexts
USEFUL FOR

Students studying set theory, mathematicians interested in algebraic structures, and anyone seeking to understand the foundations of equivalence relations and their proofs.

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Homework Statement


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Homework Equations


An equivalence relation on a set A, is for a,b,c in A if:
a~a
a~b => b~a
a~b and b~c => a~c

The Attempt at a Solution


It seems uncomplicated, but I don't know how I would write down a proof. The book I'm using is Topics in Algebra, 1st Edition Herstein
 
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What if there were some element a \in A which wasn't related to any other member of A?
 
In other words, consider A= {1, 2, 3} and the relation is {(1, 1), (1,2), (2,1), (2,2)},
 
HallsofIvy said:
In other words, consider A= {1, 2, 3} and the relation is {(1, 1), (1,2), (2,1), (2,2)},

I don't understand this. I think equivalence classes are generalized equal signs for some property. So (1,1) I understand, but how so for (1,2)?
 

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