Engineering: Reports
http://hdl.handle.net/10092/611
2016-08-29T10:10:53ZTree reconstruction via a closure operation on partial splits
http://hdl.handle.net/10092/12628
Tree reconstruction via a closure operation on partial splits
Semple, Charles; Steel, M. A.
A fundamental problem in biological classification is the reconstruction
of phylogenetic trees for a set X of species from a collection of either
subtrees or qualitative characters. This task is equivalent to tree reconstruction
from a set of partial X-splits (bipartitions of subsets of X). In this paper,
we define and analyse a "closure" operation for partial X-splits that was informally
proposed by Meacham [5]. In particular, we establish a sufficient
condition for such an operation to reconstruct a tree when there is essentially
only one tree that displays the partial X-splits. This result exploits a recent
combinatorial result from [2].
1999-01-01T00:00:00ZTuberculosis spread in possum networks
http://hdl.handle.net/10092/12627
Tuberculosis spread in possum networks
De Jong, Jamie
Since the late 1960's the prevalence of bovine tuberculosis in New Zealand livestock has been associated with
nearby possum populations. In order for the disease to be controlled it is important to understand how it is spread
between possums. In this report we investigate how certain factors ( e.g. Death Rate, Meeting Rates, No. of
Contacts) impact on how far and how quickly tuberculosis spreads within a modeled network of possums. This gives
an indication of which factors are important when dealing with a real population.
2012-01-01T00:00:00ZA smalltalk queueing network simulator
http://hdl.handle.net/10092/12590
A smalltalk queueing network simulator
Irwin, Warwick
This report gives complete documentation for a working implementation of a discrete, event driven Smalltalk-80 modelling context described in Goldberg and Robson "Smalltalk-80: The Language and its Implementation". It also documents DEMOS-derived enhancements to this simulation system and methods for improved presentation of results. The system is running under Apple's level0 image on a Macintosh plus computer. It uses only standard Smalltalk-80 and will be portable to any other standard Smalltalk system. An extremely brief introduction to Smalltalk, source code and example programs are given as appendices.
1989-01-01T00:00:00ZThe difficulty of constructing a leaf-labelled tree including or avoiding given subtrees
http://hdl.handle.net/10092/12577
The difficulty of constructing a leaf-labelled tree including or avoiding given subtrees
Ng, Meei Pyng; Steel, M.; Wormald, N.
Given a set of trees with leaves labelled from a set L, is there a
tree T with leaves labelled by L such that each of the given trees is
homeomorphic to a subtree of T? This question is known to be NPcomplete
in general, but solvable in polynomial time if all the given
trees have one label in common ( equivalently, if the given trees are
rooted). Here we show that this problem is NP-complete even if there
are two labels x and y such that each given tree contains x or y. On
the other hand, we show that the question of whether a fully resolved
(binary) tree exists which has no subtree homeomorphic to one of
the given ones is NP-complete, even when the given trees are rooted.
This sheds some light on the complexity of determining whether a
probability assignment to trees is coherent.
1995-01-01T00:00:00Z