2,835 research outputs found

    Constructing symplectic forms on 4-manifolds which vanish on circles

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    Given a smooth, closed, oriented 4-manifold X and alpha in H_2(X,Z) such that alpha.alpha > 0, a closed 2-form w is constructed, Poincare dual to alpha, which is symplectic on the complement of a finite set of unknotted circles. The number of circles, counted with sign, is given by d = (c_1(s)^2 -3sigma(X) -2chi(X))/4, where s is a certain spin^C structure naturally associated to w.Comment: Published by Geometry and Topology at http://www.maths.warwick.ac.uk/gt/GTVol8/paper20.abs.htm

    Reconstructing 4-manifolds from Morse 2-functions

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    Given a Morse 2-function f:X4→S2f: X^4 \to S^2, we give minimal conditions on the fold curves and fibers so that X4X^4 and ff can be reconstructed from a certain combinatorial diagram attached to S2S^2. Additional remarks are made in other dimensions.Comment: 13 pages, 10 figures. Replaced because the main theorem in the original is false. The theorem has been corrected and counterexamples to the original statement are give

    Anacharsis Cloots

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    A Syllabus of Errors

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    Why is Our Food Making Us Sick?

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    The crowded, stressful conditions on factory farms are not only horrific for animals; they can have devastating implications for human healt

    A Killer Show

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    An excerpt from the forthcoming book Death at SeaWorld takes a hard-hitting look at the marine mammal display industry in the wake of the February 2010 trainer death at SeaWorld Orlando
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