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Theorem

Sylvester-Gallai Theorem

Geometry

The Sylvester-Gallai Theorem states that given a finite set of points in the plane that are not all collinear, there always exists a line passing through exactly two of them. First posed as a problem by James Joseph Sylvester and later proved by Tibor Gallai, it is a foundational result in combinatorial geometry.

Facts
Statement
The Sylvester-Gallai theorem in geometry states that every finite set of points in the Euclidean plane has a line that passes through exactly two of the points or a line that passes through all of them. 1
Proof Year
1944 1
Classification
Statement Form
Existence Theorem 1
Connections

Has Statement Form

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

Sources
1. Sylvester-Gallai Theorem (Wikipedia)
Wikimedia Foundation
  • Lead paragraph, first sentence
    The Sylvester-Gallai theorem in geometry states that every finite set of points in the Euclidean plane has a line that passes through exactly two of the points or a line that passes through all of them.
  • Lead paragraph, naming sentence
    It is named after James Joseph Sylvester, who posed it as a problem in 1893, and Tibor Gallai, who published one of the first proofs of this theorem in 1944.
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