# Subplane of affine plane

From Groupprops

This term is related to: incidence geometry

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Template:Affine plane-subset property

## Definition

A **subplane** of an affine plane is a subset of the point-and-line set that is an affine plane with the induced incidence structure satisfying the further condition that two lines are parallel in the subset if and only if they are parallel in the whole affine plane.

## References

*Finite Geometries* by Peter Dembowski, *Chapter 3. Projective and affine planes*