Class Equation for Conjugation Actions in A_4, D_8, and D_{10}

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SUMMARY

The discussion focuses on deriving the Class Equation for groups acting on themselves by conjugation, specifically for the groups A_4, D_8, and D_{10}. The user successfully calculates the orbits for D_8, identifying the orbits as <1>, , and , with respective elements. The next step involves explicitly describing the set-theorem and numerical forms of the Class Equation for D_8, which requires further elaboration on the centralizers and conjugacy classes.

PREREQUISITES
  • Understanding of group theory concepts, particularly conjugation actions.
  • Familiarity with the specific groups A_4, D_8, and D_{10} and their properties.
  • Knowledge of orbit-stabilizer theorem and its application in group actions.
  • Ability to compute centralizers and conjugacy classes within groups.
NEXT STEPS
  • Research the Class Equation for A_4, focusing on its conjugacy classes and centralizers.
  • Study the Class Equation for D_{10} and compare it with D_8.
  • Explore the orbit-stabilizer theorem in detail to solidify understanding of group actions.
  • Examine examples of conjugacy classes in symmetric and dihedral groups for practical application.
USEFUL FOR

Students and researchers in abstract algebra, particularly those studying group theory, as well as educators looking for examples of conjugation actions and Class Equations in specific groups.

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hi, any hints to give me a good idea on how to solve this question would be greatly appreciated:

Question:
let G be a group acting on itself by conjugation, g . x = gxg^{-1}

Describe the set-theorem and numerical forms of the Class Equation for these actions explicitly when

(i) G = A_4
(ii) G = D_8
(iii) G = D_{10}

thanx :)
 
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ok let me try part (ii) G = D_8

my working:
------------------------------------------------------------------------
Firstly D_8 = [1,x,x^2,x^3,y,xy,x^2y,x^3y]
x^4 = 1, y^2 = 1, yx = x^3y

If we calculate the orbits then we have:
orbit of <1> = {1}

<x>:
(1)x(1^{-1}) = x,
(x)x(x)^{-1} = x,
(x^2)x(x^2)^{-1} = x,
(x^3)x(x^3)^{-1} = x,
(y)x(y)^{-1} = x^2yy=x^2,
(xy)x(xy)^{-1} = xyxx^3y=xx^2yx^3y=x^6=x^2,
(x^2y)x(x^2y)^{-1} = x^2yxx^2y=x^2x^2yx^2y=x^4yx^2y=x^6yy=x^6y^2=x^6=x^2,
(x^3y)x(x^3y)^{-1} = x^3yxxy=x^3x^2yxy=x^3x^2x^2yy=x^7y^2=x^7=x^3,
so orbit of <x> = <x^2> = <x^3> = {x,x^2,x^3}

similarly,
<y>:
(1)y(1^{-1}) = y,
(x)y(x)^{-1} = x^3y,
(x^2)y(x^2)^{-1} = x^2y,
(x^3)y(x^3)^{-1} = xy,
(y)y(y)^{-1} = y,
(xy)y(xy)^{-1} = x^3y,
(x^2y)y(x^2y)^{-1} = x^2y,
(x^3y)y(x^3y)^{-1} =xy,
so orbit of <y> = <xy> <x^2y> = <x^3y> = {y,xy,x^2y,x^3y}

concluding, the if D_8 cuts on itself by conjugation, the orbits are:
<1> = {1}
<x> = <x^2> = <x^3> = {x,x^2,x^3}
<y> = <xy> = <x^2y> = <x^3y> = {y,xy,x^2y,x^3y}
------------------------------------------------------------------------

i believe I've done the hard part: so from here how would i descibe explicitly, the set theorem and numerical forms of the class equation for D_8 ? thanks :)
 

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