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.
Over , a cyclic group of order has exactly irreducible representations up to equivalence, represented by the characters with
Example
Let be a cyclic group of order . Over , the irreducible representations of are all one-dimensional, and up to equivalence they are represented by the degree-one characters
Facts & Assumptions
Given: A cyclic group of order .
Over an algebraically closed field, every endomorphism of an irreducible representation is scalar (Over an algebraically closed field, every endomorphism of an irreducible representation is scalar).
A splitting field for is a field over which every irreducible representation has scalar endomorphism ring, and then every irreducible representation of a finite abelian group is one-dimensional (A splitting field for a finite group: every irreducible representation has scalar endomorphism ring, Every irreducible representation of a finite abelian group over a splitting field is one-dimensional).
Equivalence classes of degree-one representations are exactly homomorphisms to the unit group , and each such homomorphism has the normalized representative on (Equivalence classes of degree-one representations are exactly homomorphisms ; equivalently they factor through , and they form an abelian group).
Every nonconstant complex polynomial splits, and when splits over a field of characteristic not dividing , the -th roots of unity form a cyclic group of order exactly (Every nonconstant polynomial in splits into linear factors, is separable over exactly when the characteristic does not divide , and then a splitting field carries distinct -th roots of unity, The group of -th roots of unity in a field, and primitive -th roots of unity).
Verification
By [L1], the field satisfies the scalar-endomorphism condition of [L2], so it is a splitting field for the finite group . Since is abelian, [L2] makes every irreducible complex representation of one-dimensional.
By [L3], every irreducible representation of is equivalent to a normalized degree-one representation on , hence to a homomorphism . Because , such a homomorphism is determined by the value , and the relation forces . Conversely, if , then is well defined and multiplicative.
By [L4], the polynomial splits over and has exactly distinct roots there, namely the elements of . So step 2.1 produces exactly equivalence classes of irreducible complex representations, represented by the normalized characters with .
Depends on
- Over an algebraically closed field, every endomorphism of an irreducible representation is scalar
- Every nonconstant polynomial in $\mathbb C[x]$ splits into linear factors
- The subgroup $\langle S \rangle$ generated by a subset, the cyclic subgroup $\langle g \rangle$, and cyclic groups
- The group $\mu_n(K)$ of $n$-th roots of unity in a field, and primitive $n$-th roots of unity
- A splitting field for a finite group: every irreducible representation has scalar endomorphism ring
- Equivalence classes of degree-one representations are exactly homomorphisms $G\to k^{\times}$; equivalently they factor through $G/G'$, and they form an abelian group
- Every irreducible representation of a finite abelian group over a splitting field is one-dimensional
- $t^{n}-1$ is separable over $K$ exactly when the characteristic does not divide $n$, and then a splitting field carries $n$ distinct $n$-th roots of unity
Used by
- FALSE: every degree-one representation is trivial False statement
Dependency tree · two levels
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Sources
- Pavel Etingof et al., Introduction to Representation Theory, Section 3.3 (standard reference, not scraped)