6
votes
1answer
255 views

When is a 0-1 matrix a one-intersection incidence matrix?

The following problem is what motivated my previous MO question. It is easily seen that for any given 0-1 matrix $M$, one can always find a set $\mathcal P$ of points, and a set $\mathcal C$ of ...
0
votes
1answer
210 views

About a graph embedding from R^3 to…

I was working on something and stumbled upon the following situation. I have in front of me a configuration $L$ of lines in $\mathbb{R}^{3}$ and say I consider the graph $G$ having as vertex set $L$ ...