نتایج جستجو برای: the adams equivalence theory
تعداد نتایج: 16144471 فیلتر نتایج به سال:
See [Oli04]. In [AdKech00], Adams and Kechris showed that the relation of equality on Borel sets (and therefore, any Borel equivalence relation whatsoever) is Borel reducible to the equivalence relation of Borel bireducibility. (In somewhat finer terms, they showed that the partial order of inclusion on Borel sets is Borel reducible to the quasi-order of Borel reducibility.) Their technique was...
the aim of this paper is to study co-prolongations of central extensions. we construct the obstruction theory forco-prolongations and classify the equivalence classes of these by kernels of homomorphisms between 2-dimensional cohomology groups of groups.
in this thesis, first the notion of weak mutual associativity (w.m.a.) and the necessary and sufficient condition for a $(l,gamma)$-associated hypersemigroup $(h, ast)$ derived from some family of $lesssim$-preordered semigroups to be a hypergroup, are given. second, by proving the fact that the concrete categories, semihypergroups and hypergroups have not free objects we will introduce t...
We analyze the technique used by Adams and Kechris (2000) to obtain their results about Borel reducibility of countable Borel equivalence relations. Using this technique, we show that every Σ1 equivalence relation is Borel reducible to the Borel bi-reducibility of countable Borel equivalence relations. We also apply the technique to two other classes of essentially uncountable Borel equivalence...
this research concentrates on the lithostratigraphy, biostratigraphy, microfacies and sedimentary environment of the asmari and gachsaran formations at southwest firuzabad. the thickness of the studied section in all 608.95 meters that 220.8 meters belong to the asmari formation and 387.95 meters belong to the gachsaran formation (champe and mol members). in the study area, the asmari formation...
iv abstract this study examined the linguistic behaviors of two iranian efl teachers each of them teaching learners of two similar proficiency levels, a beginner level and an intermediate level, to investigate the relationship between the learners proficiency levels and the amounts and purposes for l1 use by the two teachers. the study was carried out to investigate whether there were differe...
there are two major theories of measurement in psychometrics: classical test theory (ctt) and item-response theory (irt). despite its widespread and long use, ctt has a number of shortcomings, which make it problematic to be used for practical and theoretical purposes. irt tries to solve these shortcomings, and provide better and more dependable answers. one of the applications of irt is the as...
among the low–dimensional allotropes of carbon, nanotubes and graphene have attracted very much attention from nano–science and nanotechnology specialists. they have been proposed as building blocks in nanometer device engineering. however, these structures are not defect–free. in this thesis, we focused on defective carbon nanotubes and graphene, and studied the effect of couple of very common...
from 1950s onward, new theories and critical approaches burgeoned across humanities. these theories were context-oriented; as a result, the analysis of discursive practices gained significance. thus, social, political, historical and cultural discourses that have been hitherto marginalized and considered inferior to literary texts, were introduced as important texts to be analyzed by critics. o...
in this thesis, using concepts of wavelets theory some methods of the solving optimal control problems (ocps). governed by time-delay systems is investigated. this thesis contains two parts. first, the method of obtaining of the ocps in time delay systems by linear legendre multiwavelets is presented. the main advantage of the meth...
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