6 - Symmetric groups
---dg-publish: true---
Let
Here, the identity map
The inverse function
Associativity and closure follow as properties of composition of bijections.
Let
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Let
By observing the commutative diagram above, we see that for every
Hence we claim that the map
Homomorphicity:
Surjectivity:
Let
Injectivity:
let
Let
Because left coset maps of a group are bijective They are a subset of