Search results for "Relational algebra"
showing 10 items of 20 documents
Angular momentum projection of cranked Hartree-Fock states: Application to terminating bands inA~44nuclei
2007
We present the first systematic calculations based on the angular-momentum projection of cranked Slater determinants. We propose the Iy --> I scheme, by which one projects the angular momentum I from the 1D cranked state constrained to the average spin projection of =I. Calculations performed for the rotational band in 46Ti show that the AMP Iy --> I scheme offers a natural mechanism for correcting the cranking moment of inertia at low-spins and shifting the terminating state up by ~2 MeV, in accordance with data. We also apply this scheme to high-spin states near the band termination in A~44 nuclei, and compare results thereof with experimental data, shell-model calculations, and res…
Gauge integrals and selections of weakly compact valued multifunctions
2016
In the paper Henstock, McShane, Birkhoff and variationally multivalued integrals are studied for multifunctions taking values in the hyperspace of convex and weakly compact subsets of a general Banach space X. In particular the existence of selections integrable in the same sense of the corresponding multifunctions has been considered.
Some new results on integration for multifunction
2018
It has been proven in previous papers that each Henstock-Kurzweil-Pettis integrable multifunction with weakly compact values can be represented as a sum of one of its selections and a Pettis integrable multifunction. We prove here that if the initial multifunction is also Bochner measurable and has absolutely continuous variational measure of its integral, then it is a sum of a strongly measurable selection and of a variationally Henstock integrable multifunction that is also Birkhoff integrable.
Governing Survival Probability to Distill Quantum States
2005
A quantum system interacting with a repeatedly measured one undergoes a nonunitary time evolution pushing it into some specific subspaces. We deeply investigate the origin of the relevant selection rule, bringing to the light its connection with the survival probability related with the two-system interaction. The possibility of inducing an effective dynamics in the distilled subspace just during the distillation process is demonstrated.
Optimal selection of thek best of a sequence withk stops
1997
We first consider the situation in which the decision-maker is allowed to have five choices with purpose to choose exactly the five absolute best candidates fromN applicants. The optimal stopping rule and the maximum probability of making the right five-choice are given for largeN eN, the maximum asymptotic value of the probability of the best choice being limN→∝P (win) ≈ 0.104305. Then, we study the general problem of selecting thek best of a sequence withk stops, constructing first a rough solution for this problem. Using this suboptimal solution, we find an approximation for the optimal probability valuesPk of the form $$P_k \approx \frac{1}{{(e - 1)k + 1}}$$ for any k eN.
Bayesian subset selection for additive and linear loss function
1979
Given k independent samples of common size n from k populations πj,…,πk with distribution the problem is to select a non-empty subset form {πj,…,πk}, which is associated with "good" (large) θ-values. We consider this problem from a Bayesian approach. By choosing additive and especially linear loss functions we try to fill a gap lying in between the results of Deely and Gupta (1968) and more recent papers due to Goel and Rubin (1977), Gupta and Hsu (1978) and other authors. It is shown that under acertain "normal model" Seal's procedure turns out to be Bayes w.r.t. an unrealistic loss function where as Gupta's maximunl means procedure turns out to be ( for large n) asymptotically Bayes w.r. …
Empirical Autotuning of Two-level Parallel Linear Algebra Routines on Large cc-NUMA Systems
2012
In large cc-NUMA systems the efficient use of the different levels of the memory hierarchy is not an easy task, and the performance of multithreading implementations of the libraries decreases when the number of cores used increases, so producing an important lost of efficiency. To alleviate this problem, routines with multilevel parallelism can be developed by combining OpenMP and BLAS parallelism. In that way, higher performance can be achieved, but it is necessary to develop some autotuning technique for the appropriate selection of the number of threads to use at each level. The selection can be made through theoretical models of the execution time or some installation methodology. This…
A generalized transitive closure for relational queries
1988
We augment relational algebra with a generalized transitive closure operator that allows for the efficient evaluation of a subclass of recursive queries. The operator is based on a composition operator which is as general as possible when the operator is required to be associative and when only relational algebra operators are used in its definition. The closure of such a composition can be computed using the well-known efficient algorithms designed for the computation of the usual transitive closure. Besides the case in which complete materialization of recursive relations are required, our strategy also yields an efficient solution in the case in which a selection is applied to the closur…
A relational model for unstructured documents
1987
The logical structure of a document is usually a tree in which the order of the nodes is important at least at some level of the tree. We call a document unstructured if its structure is a single-level ordered tree. The purpose of this paper is to present a many-sorted algebra for handling unstructured documents. The documents in the model are represented by relations. An algebra for handling documents of one type can be extended to an algebra for handling documents of several types. Further, an algebra for handling documents can be extended by the relational algebra for handling documents and relations in a common algebra. The model of this paper can be regarded as a part of a general docu…
Induced and reduced unbounded operator algebras
2012
The induction and reduction precesses of an O*-vector space \({{\mathfrak M}}\) obtained by means of a projection taken, respectively, in \({{\mathfrak M}}\) itself or in its weak bounded commutant \({{\mathfrak M}^\prime_{\rm w}}\) are studied. In the case where \({{\mathfrak M}}\) is a partial GW*-algebra, sufficient conditions are given for the induced and the reduced spaces to be partial GW*-algebras again.