Existenzbedingungen für Dualitäten projektiver Ebenen

In a projective plane a permutation of the set of all points and lines is constructed, using only the operations join and meet. Under certain conditions (identities in a coordinatizing ternary field; special cases of Desargues- and Pappos-theorem) this permutation is a duality. For a topological projective plane this duality proves, that point space and line space of the plane are homeomorphic.