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Abstract
A simple graph
G
is a pairwise compatibility graph (PCG) if there exists an edge-weighted tree
T with positive weights and
nonnegative numbers
d min
and
d max such that the
leaves of
T are exactly
the vertices of
G ,
and
u v is an
edge in G
if and only if the sum of weights of edges on the unique path between
u
and v in
T is at least
d min and at most
d max . We show that a
wheel on
n vertices is
a PCG if and only if
n
≤ 8 ,
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.)
Keywords
pairwise compatibility graph, PCG, phylogenetic tree, wheel
Mathematical Subject Classification 2010
Primary: 05C12, 05C78
Milestones
Received: 27 September 2018
Revised: 28 January 2019
Accepted: 30 January 2019
Published: 22 May 2019
Communicated by Ann N. Trenk