Proving Cauchy's Theorem with induction

  • Thread starter Thread starter beachbum300
  • Start date Start date
  • Tags Tags
    Induction Theorem
beachbum300
Messages
2
Reaction score
0

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?
 
Physics news on Phys.org
Take any non-identity element of G, say a, and use n=[G:&lt;a&gt;]|&lt;a&gt;|.
 
Prove $$\int\limits_0^{\sqrt2/4}\frac{1}{\sqrt{x-x^2}}\arcsin\sqrt{\frac{(x-1)\left(x-1+x\sqrt{9-16x}\right)}{1-2x}} \, \mathrm dx = \frac{\pi^2}{8}.$$ Let $$I = \int\limits_0^{\sqrt 2 / 4}\frac{1}{\sqrt{x-x^2}}\arcsin\sqrt{\frac{(x-1)\left(x-1+x\sqrt{9-16x}\right)}{1-2x}} \, \mathrm dx. \tag{1}$$ The representation integral of ##\arcsin## is $$\arcsin u = \int\limits_{0}^{1} \frac{\mathrm dt}{\sqrt{1-t^2}}, \qquad 0 \leqslant u \leqslant 1.$$ Plugging identity above into ##(1)## with ##u...
Back
Top