MAGMA Computational Algebra System

Shadow Spaces

Let Γ(X, ~, t, I) be an incidence geometry. Let J be a subset of I. The shadow space Γ(J) of Γis the incidence structure whose point-set is the set of flags of type J of Γand whose blocks are the J - shadows of the flags of Γ.

ShadowSpace(D,I) : IncGeom, Set -> Inc

Given an incidence geometry D and a subset I of the set of types of D, return the shadow space D(I) as an incidence structure.