Proving Cauchy's Theorem with induction

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SUMMARY

This discussion focuses on proving Cauchy's Theorem for finite abelian groups, specifically that if p is a prime dividing the order of group G, then G contains an element of order p. The proof utilizes mathematical induction, starting with base cases for n=1, n=2, and n=3, confirming the theorem holds true for these values. The inductive step involves assuming the theorem is valid for all orders less than n and suggests using a non-identity element of G to further the proof. The discussion emphasizes the importance of understanding subgroup orders in relation to the overall group order.

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  • Understanding of finite abelian groups
  • Familiarity with mathematical induction
  • Knowledge of group order and subgroup properties
  • Basic concepts of prime numbers in group theory
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  • Learn about subgroup orders and their implications in group theory
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Mathematics students, particularly those studying abstract algebra, group theory enthusiasts, and educators looking to deepen their understanding of Cauchy's Theorem and its proofs.

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Homework Statement



If p is a prime and p divides the order of G where G is a finite abelian group, then G has an element of order p. Prove without using the Fundamenthal Theorem for Finitely Generated Abelian Groups.
Hint 1: Induct on the order of G
Hint 2: Note that G/H has a smaller order than G if H is non-trivial

Homework Equations





The Attempt at a Solution


P(n): If the order of G=n and p divides the order of G, then G has an element of order p.
Base Case:
Consider n=1. Vacuously true.
Consider n=2. Since 2 is prime and 2 divides 2, then G has an element of order 2
Consider n=3. Since 3 is prime and 3 divides 3, then G has an element of order 3.
Inductive Step:
Assume P(k) is true for 0<k<n where n>3.
This is where I'm not sure of what to do next. Any suggestions?
 
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Take any non-identity element of G, say a, and use [itex]n=[G:<a>]|<a>|[/itex].
 

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