Alphabeta Math

Normal Subgroups and Quotient Groups: Examples and Counterexamples

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1 · Prerequisites
2 · Logical flowchart

3 · Items

Counterexample

A nonnormal two-element subgroup of Sym({1,2,3}) makes coset multiplication depend on representatives

Example

The three-cycle subgroup of Sym({1,2,3}) is normal and its quotient has two elements

Example

The four cosets of 4ℤ in (ℤ,+) reproduce addition modulo 4

Example

G/{e} reproduces G, while G/G is the one-element quotient group

Example

For an abelian group G, Z(G)=G and [G,G]={e}

Sources