A function γ: K → L between two geometric lattices K and L is a normalized comap if it preserves the relations: x covers or equals y, meets of modular pairs, and the minimum. The theorem, a normalized comap can be factored into an injection followed by a retraction onto a modular flat, is proved. © 1983.
Kung, J. P. S. (1983). A factorization theorem for comaps of geometric lattices. Journal of Combinatorial Theory, Series B, 34(1), 40–47. https://doi.org/10.1016/0095-8956(83)90004-7