Kenney, Toby
Toby Kenney
Associate ProfessorEmail: tkenney@mathstat.dal.ca
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Injective power objects and the axiom of choice
"The axiom of choice states that any set X of nonempty sets has a choice functioni.e. a function X > f boolean OR X satisfying f (x) is an element of x for all x is an element of X. When we want to generalise this to a ... 
The path relation for directed planar graphs in rectangles, and its relation to the free diad
In this paper, we define the path relation of a directed graph to be the relation which relates two vertices if there is a path from the first to the second. We study the restriction of this relation to paths from sources ... 
Diads and their Application to Topoi
It is well known that the category of coalgebras for a finitelimit preserving comonad on a topos is again a topos, and the category of algebras for a finitelimit preserving monad is a topos if the monad is idempotent, ... 
The General Theory of Diads
A diad is a generalisation of a monad and a comonad. The idea is that we ignore the unit or counit, and consider only the natural transformations between T and T(2). It turns out that almost all the constructions that we ... 
Graphical algebras  a new approach to congruence lattices
In 1970, H. Werner considered the question of which sublattices of partition lattices are congruence lattices for an algebra on the underlying set of the partition lattices. He showed that a complete sublattice of a partition ... 
Tensor Products of SupLattices and Generalized SupArrows
An alternative description of the tensor product of suplattices is given with yet another description provided for the tensor product in the special case of CCD suplattices. In the course of developing the latter, ... 
Hessian calculation for phylogenetic likelihood based on the pruning algorithm and its applications
No abstract available.