Dual incidence structures

Related pages

Duality principle
Dualities and polarities
Given an incidence structure we denote the transposed incidence relation by

The new incidence structure

is the so called dual incidence structure of . In words, the points of the dual incidence structure are the lines of the original structure, and the lines of the new structure are the points of our old incidence structure.

The dual incidence structure admits the same automorphisms as the original geometry.

Obviously, if A denotes an incidence matrix associated to then the transposed matrix At is the corresponding incidence matrix of the dual incidence structure.

Contributed by Hauke Klein
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