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.