Group theory MOC

Normal closure

Let 𝐺 be a group, and 𝑆 βŠ†πΊ be a subset. The normal closure ncl𝐺(𝑆) of 𝑆 is the smallest normal subgroup of 𝐺 containing 𝑆. group This is well-defined because the intersection of normal subgroups is a normal subgroup, hence

ncl𝐺(𝑆)=β‹‚{π‘βŠ΄πΊ:π‘†βŠ†π‘}

Properties

  • ncl𝐺(𝑆) has the conjugates of elements of 𝑆 as generators.


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