How statement and proof provenance work
The first chip identifies the source of the statement or construction; the second identifies the source of its local proof or verification.
- Literature-sourced: the exact statement appears in a cited source; only wording and notation differ.
- AI-adapted: a semantically identical restatement of literature-sourced material, modulo indexing, notation, and boundary cases adopted by the library.
- AI-generated: a genuinely novel statement formulated by AI, with no source for the claim itself.
These labels describe origin, not correctness: citations and verification chips remain separate evidence.
Normal subgroup: invariance under conjugation
Definition
Let be a group and let be a subgroup (Subgroup). For , write
The subgroup is normal in when
In that case write . Equivalently, every inner conjugation of maps onto itself. The connection with equality of the left and right cosets of Left and right cosets and of a subgroup is proved in Equivalent characterisations of a normal subgroup by conjugates and left and right cosets.
Depends on
Used by
- A subgroup is normal if and only if it is the kernel of a group homomorphism Corollary
- A Sylow p-subgroup is normal if and only if it is unique Corollary
- Every subgroup of index p in a finite p-group is normal Corollary
- For n≥5, the only proper nontrivial normal subgroup of Sₙ is Aₙ Corollary
- Frobenius automizer criterion for p nilpotence Corollary
- Frobenius semidirect product decomposition Corollary
- A solvable group that is not an M-group Counterexample
- Cyclic sylow does not alone imply a normal p complement Counterexample
- An internal semidirect product and a complement to a normal subgroup Definition
- Cuspidal representations and Harish-Chandra series Definition
- Free-presentation kernel data Definition
- Harish-Chandra induction and restriction for finite general linear groups Definition
- Inertia group and characters lying above a normal type Definition
- Internal direct products of finitely many normal subgroups Definition
- K₁ of a ring and the Whitehead group of a discrete group Definition
- Minimal normal subgroups and the socle of a finite group Definition
- Normal p complement and p nilpotent group Definition
- Ordered partitions and coordinate parabolics Definition
- P residual of a finite group Definition
- Permutation Weyl group and inversion length Definition
- Simple groups Definition
- Subnormal and normal series, factors, refinements, and equivalence Definition
- Supersolvable groups and monomial characters Definition
- The central product G∘_α H of two groups along an isomorphism of central subgroups Definition
- The finite residual is the intersection of the finite-index normal subgroups, and a group is residually finite when that intersection is trivial Definition
- The modular group and its action on the upper half-plane Definition
- The normal closure of a subset of a group Definition
- The p-core Oₚ(G) as the largest normal p-subgroup Definition
- The p-prime core of a finite group Definition
- The profinite topology on a group uses finite-index normal subgroups as an identity-neighbourhood basis Definition
- The quotient group G/N and coset product (gN)(hN)=ghN Definition
- Affine linear Frobenius groups over finite fields Example
- Frobenius normal two complement for S₃ Example
- S₃ as a Frobenius group Example
- The real affine group is amenable and nonunimodular Example
- The two-circle wedge has both regular and nonregular connected three-sheeted coverings Example
- V₄={1,(12)(34),(13)(24),(14)(23)} is a proper nontrivial normal subgroup of A₄ Example
- FALSE: Aₙ is simple for every n≥4 False statement
- A conjugacy class in an index-two normal subgroup remains one class or splits into two equal classes, with a centralizer criterion Lemma
- A faithful irreducible with a noncentral abelian normal subgroup is induced from a proper inertia group Lemma
…and 63 more results.
Dependency tree · two levels
6 results within two dependency steps of this one, each drawn at its shortest distance from it. An arrow runs from a result to what uses it, so the chart reads left to right and ends at this result, which carries a heavier outline. Every node is a link to that result. Click elsewhere on the chart to enlarge it.
Sources
- Encyclopedia of Mathematics, Normal subgroup (standard reference, not scraped)