748,540 research outputs found
An Introduction to Natural Computation,
ABSTRACT Coherence Spaces were defined by J. Y. Girard in Coherence Spaces are a special subcategory of Scott domains [4] having a strictly finitary structure. The objects are constructed over a set of tokens (basic elements) where a coherence (reflexive and symmetric) relation is defined. The order of information is the set inclusion relation. In this work, we introduce the Probabilistic Coherence Spaces by associating probabilistic values with the objects of coherence spaces. As a result we get a notion of partial probability associated with the partial objects of the probabilistic coherence spaces. It is possible to adopt a vector notation, introducing the Vector Coherence Spaces, so that Probabilistic Coherence Spaces can be used to represent state spaces of probabilistic processes. Since such states represent partial probabilities, computation with such states produces probabilistic approximation processes whose limits are the conventional probabilistic processes. We also study linear functions on probabilistic coherence spaces to represent those probabilistic approximation processes and conventional probabilistic limits. The aim to recast in terms of the special structure of Vector Coherence Spaces the fundamental notions of probabilistic and quantum computing One immediate application of the work is in the construction of a domain of Markov models [1] with partial probabilities
Lotfi A. Zadeh: On the man and his work
AbstractZadeh is one of the most impressive thinkers of the current time. An engineer by formation, although the range of his scientific interests is very broad, this paper only refers to his work towards reaching computation, mimicking ordinary reasoning, expressed in natural language, namely, with the introduction of fuzzy sets, fuzzy logic, and soft computing, as well as more recently, computing with words and perceptions
Optimization of supply diversity for the self-assembly of simple objects in two and three dimensions
The field of algorithmic self-assembly is concerned with the design and
analysis of self-assembly systems from a computational perspective, that is,
from the perspective of mathematical problems whose study may give insight into
the natural processes through which elementary objects self-assemble into more
complex ones. One of the main problems of algorithmic self-assembly is the
minimum tile set problem (MTSP), which asks for a collection of types of
elementary objects (called tiles) to be found for the self-assembly of an
object having a pre-established shape. Such a collection is to be as concise as
possible, thus minimizing supply diversity, while satisfying a set of stringent
constraints having to do with the termination and other properties of the
self-assembly process from its tile types. We present a study of what we think
is the first practical approach to MTSP. Our study starts with the introduction
of an evolutionary heuristic to tackle MTSP and includes results from extensive
experimentation with the heuristic on the self-assembly of simple objects in
two and three dimensions. The heuristic we introduce combines classic elements
from the field of evolutionary computation with a problem-specific variant of
Pareto dominance into a multi-objective approach to MTSP.Comment: Minor typos correcte
Bayesian Learning for Neural Networks: an algorithmic survey
The last decade witnessed a growing interest in Bayesian learning. Yet, the
technicality of the topic and the multitude of ingredients involved therein,
besides the complexity of turning theory into practical implementations, limit
the use of the Bayesian learning paradigm, preventing its widespread adoption
across different fields and applications. This self-contained survey engages
and introduces readers to the principles and algorithms of Bayesian Learning
for Neural Networks. It provides an introduction to the topic from an
accessible, practical-algorithmic perspective. Upon providing a general
introduction to Bayesian Neural Networks, we discuss and present both standard
and recent approaches for Bayesian inference, with an emphasis on solutions
relying on Variational Inference and the use of Natural gradients. We also
discuss the use of manifold optimization as a state-of-the-art approach to
Bayesian learning. We examine the characteristic properties of all the
discussed methods, and provide pseudo-codes for their implementation, paying
attention to practical aspects, such as the computation of the gradient
Towards a formalization of a two traders market with information exchange
This paper shows that Hamiltonians and operators can also be put to good use
even in contexts which are not purely physics based. Consider the world of
finance. The work presented here {models a two traders system with information
exchange with the help of four fundamental operators: cash and share operators;
a portfolio operator and an operator reflecting the loss of information. An
information Hamiltonian is considered and an additional Hamiltonian is
presented which reflects the dynamics of selling/buying shares between traders.
An important result of the paper is that when the information Hamiltonian is
zero, portfolio operators commute with the Hamiltonian and this suggests that
the dynamics are really due to the information. Under the assumption that the
interaction and information terms in the Hamiltonian have similar strength, a
perturbation scheme is considered on the interaction parameter. Contrary to
intuition, the paper shows that up to a second order in the interaction
parameter, a key factor in the computation of the portfolios of traders will be
the initial values of the loss of information (rather than the initial
conditions on the cash and shares). Finally, the paper shows that a natural
outcome from the inequality of the variation of the portfolio of trader one
versus the variation of the portfolio of trader two, begs for the introduction
of `good' and `bad' information. It is shown that `good' information is related
to the reservoirs (where an infinite set of bosonic operators are used) which
model rumors/news and external facts, whilst `bad' information is associated
with a set of two modes bosonic operators.Comment: In press in Physica Script
On the Quantum Resolution of Cosmological Singularities using AdS/CFT
The AdS/CFT correspondence allows us to map a dynamical cosmology to a dual
quantum field theory living on the boundary of spacetime. Specifically, we
study a five-dimensional model cosmology in type IIB supergravity, where the
dual theory is an unstable deformation of supersymmetric SU(N) gauge
theory on \Rbar\times S^3. A one-loop computation shows that the coupling
governing the instability is asymptotically free, so quantum corrections cannot
turn the potential around. The big crunch singularity in the bulk occurs when a
boundary scalar field runs to infinity, in finite time. Consistent quantum
evolution requires that we impose boundary conditions at infinite scalar field,
i.e. a self-adjoint extension of the system. We find that quantum spreading of
the homogeneous mode of the boundary scalar leads to a natural UV cutoff in
particle production as the wavefunction for the homogeneous mode bounces back
from infinity. However a perturbative calculation indicates that despite this,
the logarithmic running of the boundary coupling governing the instability
generally leads to significant particle production across the bounce. This
prevents the wave packet of the homogeneous boundary scalar to return close to
its initial form. Translating back to the bulk theory, we conclude that a
quantum transition from a big crunch to a big bang is an improbable outcome of
cosmological evolution in this class of five-dimensional models.Comment: 91 pages, 24 figures; v2: minor reorganization of introduction,
clarifying comments throughout; 77 pages, 22 figures;v5: error corrected
which significantly changes conclusio
Constructive Logics Part I: A Tutorial on Proof Systems and Typed Lambda-Calculi
The purpose of this paper is to give an exposition of material dealing with constructive logic, typed λ-calculi, and linear logic. The emergence in the past ten years of a coherent field of research often named logic and computation has had two major (and related) effects: firstly, it has rocked vigorously the world of mathematical logic; secondly, it has created a new computer science discipline, which spans from what is traditionally called theory of computation, to programming language design. Remarkably, this new body of work relies heavily on some old concepts found in mathematical logic, like natural deduction, sequent calculus, and λ-calculus (but often viewed in a different light), and also on some newer concepts. Thus, it may be quite a challenge to become initiated to this new body of work (but the situation is improving, there are now some excellent texts on this subject matter). This paper attempts to provide a coherent and hopefully gentle initiation to this new body of work. We have attempted to cover the basic material on natural deduction, sequent calculus, and typed λ-calculus, but also to provide an introduction to Girard\u27s linear logic, one of the most exciting developments in logic these past five years. The first part of these notes gives an exposition of background material (with the exception of the Girard-translation of classical logic into intuitionistic logic, which is new). The second part is devoted to linear logic and proof nets
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