  The circular median problem in the Double-Cut-and-Join (DCJ) distance asks to
find, for three given genomes, a fourth circular genome that minimizes the sum
of the mutual distances with the three other ones. This problem has been shown
to be NP-complete. We show here that, if the number of vertices of degree 3 in
the breakpoint graph of the three input genomes is fixed, then the problem is
tractable
