6,193 research outputs found
"Building" exact confidence nets
Confidence nets, that is, collections of confidence intervals that fill out
the parameter space and whose exact parameter coverage can be computed, are
familiar in nonparametric statistics. Here, the distributional assumptions are
based on invariance under the action of a finite reflection group. Exact
confidence nets are exhibited for a single parameter, based on the root system
of the group. The main result is a formula for the generating function of the
coverage interval probabilities. The proof makes use of the theory of
"buildings" and the Chevalley factorization theorem for the length distribution
on Cayley graphs of finite reflection groups.Comment: 20 pages. To appear in Bernoull
Quantum state discrimination bounds for finite sample size
In the problem of quantum state discrimination, one has to determine by
measurements the state of a quantum system, based on the a priori side
information that the true state is one of two given and completely known
states, rho or sigma. In general, it is not possible to decide the identity of
the true state with certainty, and the optimal measurement strategy depends on
whether the two possible errors (mistaking rho for sigma, or the other way
around) are treated as of equal importance or not. Results on the quantum
Chernoff and Hoeffding bounds and the quantum Stein's lemma show that, if
several copies of the system are available then the optimal error probabilities
decay exponentially in the number of copies, and the decay rate is given by a
certain statistical distance between rho and sigma (the Chernoff distance, the
Hoeffding distances, and the relative entropy, respectively). While these
results provide a complete solution to the asymptotic problem, they are not
completely satisfying from a practical point of view. Indeed, in realistic
scenarios one has access only to finitely many copies of a system, and
therefore it is desirable to have bounds on the error probabilities for finite
sample size. In this paper we provide finite-size bounds on the so-called Stein
errors, the Chernoff errors, the Hoeffding errors and the mixed error
probabilities related to the Chernoff and the Hoeffding errors.Comment: 31 pages. v4: A few typos corrected. To appear in J.Math.Phy
Papillitis as the prominent ocular sign in Acquired Immune Deficiency Syndrome (AIDS)
A 29-year old homosexual presented with clinical symptoms and an immunological picture of AIDS syndrome. Ocular involvement started in August 1986 with reduction of visual acuity in the right eye rapidly progressing to amaurosis. The most prominent ophthalmoscopical sign was of papillitis which had, in the beginning, the characteristics of an ischaemic optic neuropathy. Besides this, cotton-wool spots, retinal haemorrhages and limited areas of Cytomegalovirus (CMV) retinitis were found. Choroid was also involved with secondary CMV retinitis. On the other hand, sheathing of retinal vessels and Roth’s spots were absent. Although papilloedema, haemorrhages, cotton-wool exudates and CMV retinitis completely disappeared by October 1986, the general condition aggravated and the patient finally succumbed.peer-reviewe
Efficient algorithms for conditional independence inference
The topic of the paper is computer testing of (probabilistic) conditional independence (CI) implications by an algebraic method of structural imsets. The basic idea is to transform (sets of) CI statements into certain integral vectors and to verify by a computer the corresponding algebraic relation between the vectors, called the independence implication. We interpret the previous methods for computer testing of this implication from the point of view of polyhedral geometry. However, the main contribution of the paper is a new method, based on linear programming (LP). The new method overcomes the limitation of former methods to the number of involved variables. We recall/describe the theoretical basis for all four methods involved in our computational experiments, whose aim was to compare the efficiency of the algorithms. The experiments show that the LP method is clearly the fastest one. As an example of possible application of such algorithms we show that testing inclusion of Bayesian network structures or whether a CI statement is encoded in an acyclic directed graph can be done by the algebraic method
Techno-economic analysis of gas turbine-based chp plant operation under a feed-in tariff system
This paper deals with the techno-economic analysis of gas turbine-based combined heat and power production, within a current local legislation frame for the promotion of such production of energy in the Republic of Serbia. Since the legislation includes plants with electric power below 10 MW, an overview of the relevant technical characteristics for a number of appropriate gas turbines was prepared. The relevant thermodynamic parameters are calculated in order to estimate the economic feasibility of combined heat and power production using these plants. The production cost of useful heat is determined by taking into account the incomes from the sale of electricity to the electric grid under a feed-in tariff. It is compared with the production cost from an equivalent boiler for the separate production of the heat. One of the main objectives is to determine the effectiveness of the implemented legislative measures in the promotion of combined production of heat and power. Clear conclusions were drawn based on the results obtained
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