Alphabeta Math
DefinitionDefinition: AI-adaptedProof: Not applicableSession-authored (Fable 5 assisted)audited 2026-08-13
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.

Deleted-row-and-column minors, cofactors, the cofactor matrix and the adjugate over a commutative ring

Definition

Let R be a commutative ring, let n1, and let A=(aij)Mn(R), with rows and columns indexed by 0,,n1 (Finite rectangular matrices over a commutative ring, their entries, rows and columns).

For 0i,j<n, the deleted-row-and-column matrix A(i,j) is obtained by deleting row i and column j. The minor and cofactor at (i,j) are

Mij(A):=det(A(i,j)),Cij(A):=εijMij(A),

where the sign is taken in R by parity: εij:=1R when i+j is even and εij:=1R when i+j is odd. Writing this as (1)i+j is the usual abbreviation; it is the ring element 1R raised to a natural-number power in R, not a real power. When n=1, A(0,0) is the unique 0×0 matrix and its determinant is defined locally to be 1. For n>1, the determinant is the published matrix determinant (For n1, the determinant over a commutative ring by the Leibniz formula, and detA for a real matrix).

The cofactor matrix is cof(A):=(Cij(A)), and the adjugate is

adj(A):=cof(A)T,

using the published transpose operation (Entrywise ring-matrix operations, rectangular matrix products, identity matrices and transpose).

Depends on

Used by

Dependency tree · next 3 levels

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Sources