Equivalence of Subgroups in a Group

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SUMMARY

The discussion focuses on proving that the relation defined on group G, where a ~ b if a = hbk for h in subgroup H and k in subgroup K, is an equivalence relation. The proof requires demonstrating the reflexive, symmetric, and transitive properties. Specifically, for reflexivity, one must show that a ~ a holds by finding appropriate elements in H and K. For symmetry, the proof must establish that if a ~ b, then b ~ a can be derived from the definitions of the subgroups.

PREREQUISITES
  • Understanding of group theory concepts, specifically subgroups.
  • Familiarity with equivalence relations and their properties.
  • Knowledge of the definitions and operations within groups.
  • Basic proof techniques in abstract algebra.
NEXT STEPS
  • Study the properties of equivalence relations in abstract algebra.
  • Explore examples of subgroups in finite groups.
  • Learn about the application of subgroup relations in group homomorphisms.
  • Investigate the role of normal subgroups in equivalence relations.
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Students of abstract algebra, mathematicians focusing on group theory, and anyone interested in understanding the structure and properties of groups and their subgroups.

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Homework Statement


Let H and K be subgroups of the group G. Let a,b \in G and define a relation on G by a ~ b if and only if a = hbk for some h \in H and k \in K. Prove that this is an equivalence relation.

Homework Equations


a = hbk

The Attempt at a Solution


The goal is to prove the reflexive, symmetric, and transitive properties of equivalence. I was just hoping someone could help lead me in the right direction of how to start each one. Thanks!
 
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Reflexive means a~a. Can you find an element in H and another in K such that a=h.a.k?
Symmetric means a~b => b~a. So if a=h.b.k, you need to show b=h'.a.k' for some h' in H and k' in K.
Just use the definitions...
 

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