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Theorem

Sophie Germain's Theorem

Number Theory

If p is an odd prime for which 2p plus 1 is also prime (a Sophie Germain prime condition), then the first case of Fermat's Last Theorem holds for exponent p: there is no solution in integers coprime to p. It was Sophie Germain's major partial contribution toward Fermat's Last Theorem, developed in correspondence with Gauss and Legendre.

Facts
Statement
If an odd prime p has an auxiliary prime q such that no two nonzero pth powers differ by 1 modulo q and p is itself not a pth power modulo q, then at least one of x, y, z in x^p + y^p = z^p must be divisible by p^2, so the first case of Fermat's Last Theorem holds for p. 1
Proof Year
1823 1
Classification
Statement Form
Existence Theorem 1
Statement Form
Inequality 1
Statement Form
Identity or Equation 1
Connections

Has Statement Form

Equation, Concepts

Entity-backed identity for the statement-form enum value this theorem already carries, resolved to a mathematics concept by an explicit value-to-entity map (phase 3 bucket conversion, docs\design_entity_backed_browse_buckets_20260928.md). The statement-form fact itself stays on the theorem unchanged.

Entity-backed identity for the statement-form enum value this theorem already carries, resolved to a mathematics concept by an explicit value-to-entity map (phase 3 bucket conversion, docs\design_entity_backed_browse_buckets_20260928.md). The statement-form fact itself stays on the theorem unchanged.

Identity, Concepts

Entity-backed identity for the statement-form enum value this theorem already carries, resolved to a mathematics concept by an explicit value-to-entity map (phase 3 bucket conversion, docs\design_entity_backed_browse_buckets_20260928.md). The statement-form fact itself stays on the theorem unchanged.

Inequality, Concepts

Entity-backed identity for the statement-form enum value this theorem already carries, resolved to a mathematics concept by an explicit value-to-entity map (phase 3 bucket conversion, docs\design_entity_backed_browse_buckets_20260928.md). The statement-form fact itself stays on the theorem unchanged.

In Branch

Named After

Sophie Germain, Mathematicians

Derived from the theorem's own name (unambiguous possessive-token match to exactly one live mathematician entity, w-bfill-g5-0924 browse backfill)

Proved By

Sources
1. Sophie Germain's theorem (Wikipedia)
Wikimedia Foundation
  • History section, first sentence
    Germain identified such an auxiliary prime q for every prime less than 100.
  • History section, second sentence
    The theorem and its application to primes p less than 100 were attributed to Germain by Adrien-Marie Legendre in 1823.
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