70 research outputs found
A geometry of information, II: Sorkin models, and biextensional collapses
In this second part of our contribution to the workshop, we look in more detail at the Sorkin model, its relationship to constructions in Chu space theory, and then compare it with the Nerve constructions given in the first part
Bifinite Chu Spaces
This paper studies colimits of sequences of finite Chu spaces and their
ramifications. Besides generic Chu spaces, we consider extensional and
biextensional variants. In the corresponding categories we first characterize
the monics and then the existence (or the lack thereof) of the desired
colimits. In each case, we provide a characterization of the finite objects in
terms of monomorphisms/injections. Bifinite Chu spaces are then expressed with
respect to the monics of generic Chu spaces, and universal, homogeneous Chu
spaces are shown to exist in this category. Unanticipated results driving this
development include the fact that while for generic Chu spaces monics consist
of an injective first and a surjective second component, in the extensional and
biextensional cases the surjectivity requirement can be dropped. Furthermore,
the desired colimits are only guaranteed to exist in the extensional case.
Finally, not all finite Chu spaces (considered set-theoretically) are finite
objects in their categories. This study opens up opportunities for further
investigations into recursively defined Chu spaces, as well as constructive
models of linear logic
Big Toy Models: Representing Physical Systems As Chu Spaces
We pursue a model-oriented rather than axiomatic approach to the foundations
of Quantum Mechanics, with the idea that new models can often suggest new
axioms. This approach has often been fruitful in Logic and Theoretical Computer
Science. Rather than seeking to construct a simplified toy model, we aim for a
`big toy model', in which both quantum and classical systems can be faithfully
represented - as well as, possibly, more exotic kinds of systems.
To this end, we show how Chu spaces can be used to represent physical systems
of various kinds. In particular, we show how quantum systems can be represented
as Chu spaces over the unit interval in such a way that the Chu morphisms
correspond exactly to the physically meaningful symmetries of the systems - the
unitaries and antiunitaries. In this way we obtain a full and faithful functor
from the groupoid of Hilbert spaces and their symmetries to Chu spaces. We also
consider whether it is possible to use a finite value set rather than the unit
interval; we show that three values suffice, while the two standard
possibilistic reductions to two values both fail to preserve fullness.Comment: 24 pages. Accepted for Synthese 16th April 2010. Published online
20th April 201
Branching Space-Times and Parallel Processing
There is a remarkable similarity between some mathematical objects used in the Branching Space-Times framework and those appearing in computer science in the fields of event structures for concurrent processing and Chu spaces. This paper introduces the similarities and formulates a few open questions for further research, hoping that both BST theorists and computer scientists can benefit from the project
A geometry of information, I: Nerves, posets and differential forms
The main theme of this workshop (Dagstuhl seminar 04351) is `Spatial
Representation: Continuous vs. Discrete'. Spatial representation has two
contrasting but interacting aspects (i) representation of spaces' and (ii)
representation by spaces. In this paper, we will examine two aspects that are
common to both interpretations of the theme, namely nerve constructions and
refinement. Representations change, data changes, spaces change. We will
examine the possibility of a `differential geometry' of spatial representations
of both types, and in the sequel give an algebra of differential forms that has
the potential to handle the dynamical aspect of such a geometry. We will
discuss briefly a conjectured class of spaces, generalising the Cantor set
which would seem ideal as a test-bed for the set of tools we are developing.Comment: 28 pages. A version of this paper appears also on the Dagstuhl
seminar portal http://drops.dagstuhl.de/portals/04351
Operational theories and Categorical quantum mechanics
A central theme in current work in quantum information and quantum
foundations is to see quantum mechanics as occupying one point in a space of
possible theories, and to use this perspective to understand the special
features and properties which single it out, and the possibilities for
alternative theories. Two formalisms which have been used in this context are
operational theories, and categorical quantum mechanics. The aim of the present
paper is to establish strong connections between these two formalisms. We show
how models of categorical quantum mechanics have representations as operational
theories. We then show how nonlocality can be formulated at this level of
generality, and study a number of examples from this point of view, including
Hilbert spaces, sets and relations, and stochastic maps. The local, quantum,
and no-signalling models are characterized in these terms.Comment: 37 pages, updated bibliograph
Ludics without Designs I: Triads
In this paper, we introduce the concept of triad. Using this notion, we
study, revisit, discover and rediscover some basic properties of ludics from a
very general point of view.Comment: In Proceedings LINEARITY 2014, arXiv:1502.0441
On Game Formats and Chu Spaces
It is argued that virtually all coalitional, strategic and extensive game formats as currently employed in the extant game-theoretic literature may be presented in a natural way as discrete nonfull or even-under a suitable choice of morphisms- as full subcategories of Chu (Poset 2).
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