Is he above or below ground?

I am not sure, I do not know.

I never see him come or go.

Here are some suggestions:

- Make sure you spelled his last name correctly.
- Check under his desk.
- If all else fails, this advice is often useful not only for locating professors, but also for locating Marks, and indeed, just about anyone or anything. Or so he claims.

Perhaps the reason that you came,

Is that you seek some paper with name.

- How to Cover Most of a Point Set with a V-Shape of Minimum Width

by Boris Aronov, John Iacono, Özgür Özkan and M. Yagnatinsky

in CCCG 2013 - How To Place a Point to Maximize Angles

by Boris Aronov and M. Yagnatinsky

in CCCG 2013 - Sum of Squared Edges for MST of a Point Set in a Unit Square

by O. Aichholzer, S.R. Allen, G. Aloupis, L. Barba, P. Bose, J.L. De Carufel, J. Iacono, S. Langerman, D.L. Souvaine, P. Taslakian, M. Yagnatinsky

in JCDCGG 2013