Friday, November 9, 2012

Abstract Algebra Glimpse

As we know magma , semigroup , Monoid , Group and Ring , field  from definition let's see some good features and examples of them .

Group example : 1. (Zn,+) Zn = {0,1,...(n-1)} , '+' is addition modulo n
             2. (Un,.)  Un = {0< x < n | x ⊥ n ( relatively prime )} , '.' is multiplication modulo n
           
An algebraic structure G = (A,P)| Γ have substructure H = (B,P)| Γ  ⇔  B ⊆ A  Γ(B,P) = true .
i.e according to above definition of G,H : (H ≤ G)    (B ⊆ A  Γ(B,P) = true)  

If (G,+) , (H,+) are groups then (H ≤ G)   ∀ x,y ∈ H x+(-y)  ∈ H

left and right cosets of H ≤ G are xH,Hx respectively where x   ∈ 

1. Two left/right cosets are either equal or disjoint .
2. If xH = Hx ( H,x are as previous ) then H ◅ G (Normal Subgroup)

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