3,392 research outputs found

    Night In The Jungle, 1962

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    The visual boundary of Z^2

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    We introduce ideas from geometric group theory related to boundaries of groups. This is a mostly expository paper. We consider the visual boundary of a free abelian group, and show that it is an uncountable set with the trivial topology

    Monodromy action on unknotting tunnels in fiber surfaces

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    The second author showed that a tunnel of tunnel number one, fibered link in S³ can be isotoped to lie as a properly embedded arc in the fiber surface of the link. In this paper, we observe that this is true for fibered links in any 3-manifold, we analyze how the arc behaves under the monodromy action, and we show that the tunnel arc is nearly clean, with the possible exception of twisting around the boundary of the fiber

    High distance knots in closed 3-manifolds

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    Let M be a closed 3-manifold with a given Heegaard splitting. We show that after a single stabilization, some core of the stabilized splitting has arbitrarily high distance with respect to the splitting surface. This generalizes a result of Minsky, Moriah, and Schleimer for knots in S^3. We also show that in the complex of curves, handlebody sets are either coarsely distinct or identical. We define the coarse mapping class group of a Heeegaard splitting, and show that if (S, V, W) is a Heegaard splitting of genus greater than or equal to 2, then the coarse mapping class group of (S,V,W) is isomorphic to the mapping class group of (S, V,W).Comment: Certain misstatements about the pair of pants decompositions constructed for reducible Heegaard splittings have been corrected. The paper has also been restructured some to aid the exposition of the proof. Details have been provided for the end of the proof of the main theorem. And the first author's name has been change

    Indicators of School Crime and Safety: 2013

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    A joint effort by the Bureau of Justice Statistics and National Center for Education Statistics, this annual report examines crime occurring in schools and colleges. This report presents data on crime at school from the perspectives of students, teachers, principals, and the general population from an array of sources--the National Crime Victimization Survey, the School Crime Supplement to the National Crime Victimization Survey, the Youth Risk Behavior Survey, the School Survey on Crime and Safety, the School and Staffing Survey and the Campus Safety and Security Survey
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