84,959 research outputs found
The classical origin of modern mathematics
The aim of this paper is to study the historical evolution of mathematical
thinking and its spatial spreading. To do so, we have collected and integrated
data from different online academic datasets. In its final stage, the database
includes a large number (N~200K) of advisor-student relationships, with
affiliations and keywords on their research topic, over several centuries, from
the 14th century until today. We focus on two different topics, the evolving
importance of countries and of the research disciplines over time. Moreover we
study the database at three levels, its global statistics, the mesoscale
networks connecting countries and disciplines, and the genealogical level
ROOT - A C++ Framework for Petabyte Data Storage, Statistical Analysis and Visualization
ROOT is an object-oriented C++ framework conceived in the high-energy physics
(HEP) community, designed for storing and analyzing petabytes of data in an
efficient way. Any instance of a C++ class can be stored into a ROOT file in a
machine-independent compressed binary format. In ROOT the TTree object
container is optimized for statistical data analysis over very large data sets
by using vertical data storage techniques. These containers can span a large
number of files on local disks, the web, or a number of different shared file
systems. In order to analyze this data, the user can chose out of a wide set of
mathematical and statistical functions, including linear algebra classes,
numerical algorithms such as integration and minimization, and various methods
for performing regression analysis (fitting). In particular, ROOT offers
packages for complex data modeling and fitting, as well as multivariate
classification based on machine learning techniques. A central piece in these
analysis tools are the histogram classes which provide binning of one- and
multi-dimensional data. Results can be saved in high-quality graphical formats
like Postscript and PDF or in bitmap formats like JPG or GIF. The result can
also be stored into ROOT macros that allow a full recreation and rework of the
graphics. Users typically create their analysis macros step by step, making use
of the interactive C++ interpreter CINT, while running over small data samples.
Once the development is finished, they can run these macros at full compiled
speed over large data sets, using on-the-fly compilation, or by creating a
stand-alone batch program. Finally, if processing farms are available, the user
can reduce the execution time of intrinsically parallel tasks - e.g. data
mining in HEP - by using PROOF, which will take care of optimally distributing
the work over the available resources in a transparent way
Methods For Fuzzy Demand Assessment For IT Specialties
The rapid development of information technologies and their penetration into various spheres of human activity cause a sharply increased demand for IT specialists, in many countries of the world far exceeding the supply on them. High rates of technological transformation contribute to the diversification of the IT segment of the labor market, on the one hand, stimulate the disappearance of some and the emergence of new IT specialties, on the other. This creates a discrepancy between the structure of IT-related education and the labor market demand for IT specialists of the required profile and determines the relevance of developing methods for assessing the demand for IT specialties.This article is devoted to the study and solution of the problem of identifying the demand for IT specialties in the absence of accurate and complete information about the situation in the IT market segment. For the assessment of IT specialties and their ranking by the degree of demand in the labor market, the tasks of making individual and group decisions in the context of fuzzy initial information are formulated and solved. The methodological basis of the tasks posed is multi-criteria decision support methods based on fuzzy relations of expert preferences.The proposed approach as a mathematical tool for minimizing the structural imbalance of supply and demand for IT specialties is one of the components of the system of intellectual management of the labor market of IT specialists. The latter is designed to support the adoption of scientifically based management decisions to eliminate the mismatch of supply and demand in the IT segment of the labor market in professional, quantitative and qualitative sections
Explicit and spontaneous breaking of SU(3) into its finite subgroups
We investigate the breaking of SU(3) into its subgroups from the viewpoints
of explicit and spontaneous breaking. A one-to-one link between these two
approaches is given by the complex spherical harmonics, which form a complete
set of SU(3)-representation functions. An invariant of degrees p and q in
complex conjugate variables corresponds to a singlet, or vacuum expectation
value, in a (p,q)-representation of SU(3). We review the formalism of the
Molien function, which contains information on primary and secondary
invariants. Generalizations of the Molien function to the tensor generating
functions are discussed. The latter allows all branching rules to be deduced.
We have computed all primary and secondary invariants for all proper finite
subgroups of order smaller than 512, for the entire series of groups
\Delta(3n^2), \Delta(6n^2), and for all crystallographic groups. Examples of
sufficient conditions for breaking into a subgroup are worked out for the
entire T_{n[a]}-, \Delta(3n^2)-, \Delta(6n^2)-series and for all
crystallographic groups \Sigma(X). The corresponding invariants provide an
alternative definition of these groups. A Mathematica package, SUtree, is
provided which allows the extraction of the invariants, Molien and generating
functions, syzygies, VEVs, branching rules, character tables, matrix
(p,q)_{SU(3)}-representations, Kronecker products, etc. for the groups
discussed above.Comment: 62 pages, 5 figures; the corresponding software package SUtree can be
downloaded from http://theophys.kth.se/~amerle/SUtree/SUtree.html New in v2:
Nice figure added, references added, explicit transformation matrices between
different embeddings calculated, software package update
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