ELA, Volume 11, pp. 180-191, August 2004, abstract.
The External Vertices Conjecture in Case n=4
S.W. Drury
The determinantal conjecture of M. Marcus and
G. N. de Oliveira is known in many special cases.
The case of 3-by-3 matrices was settled by N.
Bebiano, J. K. Merikoski and J. da Providencia.
The case n=4 remains open. In this article a technical
conjecture is established implying a weakened form
of the determinantal conjecture for n=4.