Axiom:Reflexivity of Betweenness

Axiom

Let $\mathsf{B}$ be the relation of betweenness.

Then the following axiom is imposed:

$\forall a, b: \mathsf{B}abb$

where $a$ and $b$ are points.

Intuition

The endpoint of a line segment is on the line segment.

Sources

• June 1999: Alfred Tarski and Steven Givant: Tarski's System of Geometry (Bull. Symb. Log. Vol. 5, no. 2: pp. 175 – 214) : p. $185$ : Axiom $12$