16,371 research outputs found
N\'eron-Severi group of a general hypersurface
In this paper we extend the well known theorem of Angelo Lopez concerning the
Picard group of the general space projective surface containing a given smooth
projective curve, to the intermediate N\'eron-Severi group of a general
hypersurface in any smooth projective variety.Comment: 14 pages, to appear on Communications in Contemporary Mathematic
Plucker-Clebsch formula in higher dimension
Let S\subset\Ps^r () be a nondegenerate, irreducible, smooth,
complex, projective surface of degree . Let be the number of
double points of a general projection of to \Ps^4. In the present paper
we prove that , with equality if and only if
is a rational scroll. Extensions to higher dimensions are discussed.Comment: 12 page
On the topology of a resolution of isolated singularities
Let be a complex projective variety of dimension with isolated
singularities, a resolution of singularities,
the exceptional locus. From Decomposition Theorem
one knows that the map
vanishes for . Assuming this vanishing, we give a short proof of
Decomposition Theorem for . A consequence is a short proof of the
Decomposition Theorem for in all cases where one can prove the vanishing
directly. This happens when either is a normal surface, or when is
the blowing-up of along with smooth and connected fibres,
or when admits a natural Gysin morphism. We prove that this last
condition is equivalent to say that the map vanishes for any , and that the pull-back
is injective. This provides a relationship between
Decomposition Theorem and Bivariant Theory.Comment: 18 page
Conditional cash transfers, adult work incentives, and poverty
Conditional cash transfer (CCT) programs aim to alleviate poverty through monetary and in-kind benefits, as well as reduce future levels of poverty by encouraging investments in education, health, and nutrition. The success of CCT programs at reducing poverty depends on whether, and the extent to which, cash transfers affect adult work incentives. The authors examine whether the PROGRESA program of Mexico affects adult participation in the labor market and overall adult leisure time, and they link these effects to the impact of the program on poverty. Using the experimental design of PROGRESA's evaluation sample, the authors find that the program does not have any significant effect on adult labor force participation and leisure time. Their findings on adult work incentives are reinforced further by the result that PROGRESA leads to a substantial reduction in poverty. The poverty reduction effects are stronger for the poverty gap and severity of poverty measures.Rural Poverty Reduction,Population Policies,Poverty Monitoring&Analysis,Health Monitoring&Evaluation
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