  A formal sequent system dealing with Menelaus' configurations is introduced
in this paper. The axiomatic sequents of the system stem from 2-cycles of
Delta-complexes. The Euclidean and projective interpretations of the sequents
are defined and a soundness result is proved. This system is decidable and its
provable sequents deliver incidence results. A cyclic operad structure tied to
this system is presented by generators and relations.
