A simple graph
is a pairwise compatibility graph (PCG) if there exists an edge-weighted tree
with positive weights and
nonnegative numbers
and
such that the
leaves of
are exactly
the vertices of
,
and
is an
edge in
if and only if the sum of weights of edges on the unique path between
and in
is at least
and at most
. We show that a
wheel on
vertices is
a PCG if and only if
,
settling an open problem proposed by Calamoneri and Sinaimeri (SIAM Review 58:3
(2016), 445–460). Our approach is based on unavoidable binary classifications of the
edges in the complement of wheels that are PCGs. (Note: during the review process
of our work, we learned that the same result has been obtained independently with
an alternative proof.)