Polarity of incidence structure

From Groupprops
Jump to: navigation, search
This term is related to: incidence geometry
View other terms related to incidence geometry | View facts related to incidence geometry


A polarity of an incidence structure is an antiautomorphism of it having order two. In other words, it is a permutation of the point-union-block-set of order two, that interchanges points with blocks, and preserves the incidence relation.