83,639 research outputs found
Graded identities of block-triangular matrices
Let be an infinite field and be the algebra of upper
block-triangular matrices over . In this paper we describe a basis for the
-graded polynomial identities of , with an elementary
grading induced by an -tuple of elements of a group such that the
neutral component corresponds to the diagonal of . In
particular, we prove that the monomial identities of such algebra follow from
the ones of degree up to . Our results generalize for infinite fields of
arbitrary characteristic, previous results in the literature which were
obtained for fields of characteristic zero and for particular -gradings. In
the characteristic zero case we also generalize results for the algebra
with a tensor product grading, where is a
color commutative algebra generating the variety of all color commutative
algebras.Comment: 24 pages and 39 references. We have added section 5 in the text about
tensor products by color commutative superalgebra
South-South Cooperation in Times of Global Economic Crisis
For South-South cooperation, the current moment of global economic downturn is one of anxiety. South-South cooperation was born with the Non-Aligned Movement. It went through a latent period, but re-emerged in the 1990s and early 2000s. The momentum gathered when a handful of middle-income countries such as Brazil, India, Mexico and South Africa were set to improve their position as global players. They had developed some relatively successful social programmes, which they sought to share with other developing countries. Considering that conventional North-South cooperation had turned out to be of limited effectiveness, South-South cooperation gained further impetus.South-South Cooperation in Times of Global Economic Crisis
Regular black holes in gravity
In this work, we study the possibility of generalizing solutions of regular
black holes with an electric charge, constructed in general relativity, for the
theory, where is the Gauss-Bonnet invariant. This type of solution
arises due to the coupling between gravitational theory and nonlinear
electrodynamics. We construct the formalism in terms of a mass function and it
results in different gravitational and electromagnetic theories for which mass
function. The electric field of these solutions are always regular and the
strong energy condition is violated in some region inside the event horizon.
For some solutions, we get an analytical form for the function. Imposing
the limit of some constant going to zero in the function we recovered
the linear case, making the general relativity a particular case.Comment: 22 pages, 25 figures.Version published in EPJ
New York?s Brand-new Conditional Cash Transfer Programme: What if it Succeeds?
In 2007, emulating the Mexican experience, Mayor Bloomberg decided that New York City should also have its own conditional cash transfer programme (CCT). He named the programme Opportunity NYC after the Mexican Oportunidades. Is Opportunity NYC just one more CCT in the plethora of existing programmes? Or will it influence the way educational reforms have been traditionally conceptualized?New York?s Brand-new Conditional Cash Transfer Programme: What if it Succeeds?
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