3 research outputs found
Bounds on the radius and status of graphs
Two classical concepts of centrality in a graph are the median and the
center. The connected notions of the status and the radius of a graph seem to
be in no relation. In this paper, however, we show a clear connection of both
concepts, as they obtain their minimum and maximum values at the same type of
tree graphs. Trees with fixed maximum degree and extremum radius and status,
resp., are characterized. The bounds on radius and status can be transferred to
general connected graphs via spanning trees.
A new method of proof allows not only to regain results of Lin et al. on
graphs with extremum status, but it allows also to prove analogous results on
graphs with extremum radius
Neighbor Joining And Leaf Status
The Neighbor Joining Algorithm is among the most fundamental algorithmic
results in computational biology. However, its definition and correctness proof
are not straightforward. In particular, ''the question ''what does the NJ
method seek to do?'' has until recently proved somewhat elusive'' [Gascuel \&
Steel, 2006]. While a rigorous mathematical analysis is now available, it is
still considered somewhat hard to follow and its proof tedious at best. In this
work, we present an alternative interpretation of the goal of the Neighbor
Joining algorithm by proving that it chooses to merge the two taxa u and v that
maximize the ''leaf-status'', that is, the sum of distances of all leaves to
the unique u-v-path