407,467 research outputs found
On comparison of clustering properties of point processes
In this paper, we propose a new comparison tool for spatial homogeneity of
point processes, based on the joint examination of void probabilities and
factorial moment measures. We prove that determinantal and permanental
processes, as well as, more generally, negatively and positively associated
point processes are comparable in this sense to the Poisson point process of
the same mean measure. We provide some motivating results and preview further
ones, showing that the new tool is relevant in the study of macroscopic,
percolative properties of point processes. This new comparison is also implied
by the directionally convex ( ordering of point processes, which has
already been shown to be relevant to comparison of spatial homogeneity of point
processes. For this latter ordering, using a notion of lattice perturbation, we
provide a large monotone spectrum of comparable point processes, ranging from
periodic grids to Cox processes, and encompassing Poisson point process as
well. They are intended to serve as a platform for further theoretical and
numerical studies of clustering, as well as simple models of random point
patterns to be used in applications where neither complete regularity northe
total independence property are not realistic assumptions.Comment: 23 pages, 1 figure. This submission revisits and adds to ideas
concerning clustering and ordering presented in arXiv:1105.4293.
Results on associated point process in Section 3.3 are new. arXiv admin note:
substantial text overlap with arXiv:1105.429
A categorical semantics for causal structure
We present a categorical construction for modelling causal structures within
a general class of process theories that include the theory of classical
probabilistic processes as well as quantum theory. Unlike prior constructions
within categorical quantum mechanics, the objects of this theory encode
fine-grained causal relationships between subsystems and give a new method for
expressing and deriving consequences for a broad class of causal structures. We
show that this framework enables one to define families of processes which are
consistent with arbitrary acyclic causal orderings. In particular, one can
define one-way signalling (a.k.a. semi-causal) processes, non-signalling
processes, and quantum -combs. Furthermore, our framework is general enough
to accommodate recently-proposed generalisations of classical and quantum
theory where processes only need to have a fixed causal ordering locally, but
globally allow indefinite causal ordering.
To illustrate this point, we show that certain processes of this kind, such
as the quantum switch, the process matrices of Oreshkov, Costa, and Brukner,
and a classical three-party example due to Baumeler, Feix, and Wolf are all
instances of a certain family of processes we refer to as in
the appropriate category of higher-order causal processes. After defining these
families of causal structures within our framework, we give derivations of
their operational behaviour using simple, diagrammatic axioms.Comment: Extended version of a LICS 2017 paper with the same titl
Clustering, percolation and directionally convex ordering of point processes
Heuristics indicate that point processes exhibiting clustering of points have
larger critical radius for the percolation of their continuum percolation
models than spatially homogeneous point processes. It has already been shown,
and we reaffirm it in this paper, that the ordering of point processes is
suitable to compare their clustering tendencies. Hence, it was tempting to
conjecture that is increasing in order. Some numerical evidences
support this conjecture for a special class of point processes, called
perturbed lattices, which are "toy models" for determinantal and permanental
point processes. However, the conjecture is not true in full generality, since
one can construct a Cox point process with degenerate critical radius ,
that is larger than a given homogeneous Poisson point process.
Nevertheless, we are able to compare some nonstandard critical radii related,
respectively, to the finiteness of the expected number of void circuits around
the origin and asymptotic of the expected number of long occupied paths from
the origin in suitable discrete approximations of the continuum model. These
new critical radii sandwich the "true" one. Surprisingly, the inequalities for
them go in opposite directions, which gives uniform lower and upper bounds on
for all processes smaller than some given process. In fact, the
above results hold under weaker assumptions on the ordering of void
probabilities or factorial moment measures only. Examples of point processes
comparable to Poisson processes in this weaker sense include determinantal and
permanental processes. More generally, we show that point processes
smaller than homogeneous Poisson processes exhibit phase transitions in certain
percolation models based on the level-sets of additive shot-noise fields, as
e.g. -percolation and SINR-percolation.Comment: 48 pages, 6 figure
La cuenca del Salado: uso y posibilidades de sus recursos pesqueros.
The fishing resources of the Salado Basin are extraordinary important in the context of the inland waters of Argentina. However, the diversity of landscapes in the basin and the lack of continuity in the regional planning , have made difficult a proper management of the fishing resources. This paper has a general overview of the main aspects related to the fishing fauna of the region, with a natural point of view of the processes and mechanisms of the management. A description of the fishes basin community and the identification of the species with commercial and game interests is included . We describe the different fishing gears used in the province for game, commercial and scientific fishing. We review the criteria of diagnosis of the silver side population as a main resource of fishing interest and under this point of view we propose new outlooks to promote a proper management of the resources and its sustainable use.
We identify the different kinds of fisheries that are common in the basin and we make a survey of the related socioeconomic aspects. Moreover, we analyze the development of a new institutional and regulatory frame in order to optimize the management of the fishing resources. Finally, we define criteria for ordering and conserving such resources and identify conflict points and requirements for its sustainable use in the context of new
proposals for the public policies
Effects of rhythm on memory for spoken sequences : a model and tests of its stimulus-driven mechanism
Immediate memory for spoken sequences depends on their rhythm – different levels of accuracy and patterns of error are seen according to the way in which items are spaced in time. Current models address these phenomena only partially or not at all. We investigate the idea that temporal grouping effects are an emergent property of a general serial ordering mechanism based on a population of oscillators locally-sensitive to amplitude modulations on different temporal scales. Two experiments show that the effects of temporal grouping are independent of the predictability of the grouping pattern, consistent with this model’s stimulus-driven mechanism and inconsistent with alternative accounts in terms of top-down processes. The second experiment reports detailed and systematic differences in the recall of irregularly grouped sequences that are broadly consistent with predictions of the new model. We suggest that the bottom-up multi-scale population oscillator (or BUMP) mechanism is a useful starting point for a general account of serial order in language processing more widely
Cognition according to Quantum Information: Three Epistemological Puzzles Solved
The cognition of quantum processes raises a series of questions about ordering and information connecting the states of one and the same system before and after measurement: Quantum measurement, quantum in-variance and the non-locality of quantum information are considered in the paper from an epistemological viewpoint.
The adequate generalization of ‘measurement’ is discussed to involve the discrepancy, due to the fundamental Planck constant, between any quantum coherent state and its statistical representation as a statistical ensemble after measurement. Quantum in-variance designates the relation of any quantum coherent state to the corresponding statistical ensemble of measured results. A set-theory corollary is the curious in-variance to the axiom of choice: Any coherent state excludes any well-ordering and thus excludes also the axiom of choice. However the above equivalence requires it to be equated to a well-ordered set after measurement and thus requires the axiom of choice for it to be able to be obtained. Quantum in-variance underlies quantum information and reveals it as the relation of an unordered quantum “much” (i.e. a coherent state) and a well-ordered “many” of the measured results (i.e. a statistical ensemble). It opens up to a new horizon, in which all physical processes and phenomena can be interpreted as quantum computations realizing relevant operations and algorithms on quantum information. All phenomena of entanglement can be described in terms of the so defined quantum information. Quantum in-variance elucidates the link between general relativity and quantum mechanics and thus, the problem of quantum gravity.
The non-locality of quantum information unifies the exact position of any space-time point of a smooth trajectory and the common possibility of all space-time points due to a quantum leap. This is deduced from quantum in-variance. Epistemology involves the relation of ordering and thus a generalized kind of information, quantum one, to explain the special features of the cognition in quantum mechanics
Laplace Functional Ordering of Point Processes in Large-scale Wireless Networks
Stochastic orders on point processes are partial orders which capture notions
like being larger or more variable. Laplace functional ordering of point
processes is a useful stochastic order for comparing spatial deployments of
wireless networks. It is shown that the ordering of point processes is
preserved under independent operations such as marking, thinning, clustering,
superposition, and random translation. Laplace functional ordering can be used
to establish comparisons of several performance metrics such as coverage
probability, achievable rate, and resource allocation even when closed form
expressions of such metrics are unavailable. Applications in several network
scenarios are also provided where tradeoffs between coverage and interference
as well as fairness and peakyness are studied. Monte-Carlo simulations are used
to supplement our analytical results.Comment: 30 pages, 5 figures, Submitted to Hindawi Wireless Communications and
Mobile Computin
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