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What's behind the background?

It's a picture I generated as part of a project with
Alessandra Iozzi
investigating algebraic compactifications of $SL(2,\RR)$. The small
regions are fundamental domains for the action of the symmetric group
$S_5$ on (a subset of) $\RR^2$, and the colored numbers tell which
permutations move which sides where. The quotient space is the moduli
space of algebraic compactifications of $SL(2,\RR)$ which lie in the
five-dimensional torus $T^5$.

Here is a clearer image:

A couple of the papers on
my [p]reprints page are related to this
project -- the ones with "boundary compactifications" inthe title.