We owe the T-shirt design and our 2010 contest logo to
Dr. Martin Laubinger, a former graduate
student of LSU Math Department.
This figure shows the Serre-tree associated with the
p-adic Lie group SL2(Q2). This tree is a geometric
object which plays a role analogous to that of the upper
half plane in the theory of SL2(R). In particular,
the tree is a metric space (with a Z-valued metric), and
the group acts transitively by isometries. We
sketch how to construct the tree.