1,983,937 research outputs found
On the optimality of the neighbor-joining algorithm
The popular neighbor-joining (NJ) algorithm used in phylogenetics is a greedy
algorithm for finding the balanced minimum evolution (BME) tree associated to a
dissimilarity map. From this point of view, NJ is ``optimal'' when the
algorithm outputs the tree which minimizes the balanced minimum evolution
criterion. We use the fact that the NJ tree topology and the BME tree topology
are determined by polyhedral subdivisions of the spaces of dissimilarity maps
to study the optimality of the neighbor-joining
algorithm. In particular, we investigate and compare the polyhedral
subdivisions for . A key requirement is the measurement of volumes of
spherical polytopes in high dimension, which we obtain using a combination of
Monte Carlo methods and polyhedral algorithms. We show that highly unrelated
trees can be co-optimal in BME reconstruction, and that NJ regions are not
convex. We obtain the radius for neighbor-joining for and we
conjecture that the ability of the neighbor-joining algorithm to recover the
BME tree depends on the diameter of the BME tree
On Quantization of Black Holes
A simple argument is presented in favour of the equidistant spectrum in
semiclassical limit for the horizon area of a black hole. The following
quantization rules for the mass and horizon area are proposed:
M_N = m_p [N(N+1)]^{1/4}; A_{Nj} = 8\pi l_p^2 [\sqrt{N(N+1)} + \sqrt{N(N+1) -
j(j+1)} ]. Here both and are nonnegative integers or half-integers.Comment: 4 pages, late
Book Review: Thinking About Art
Book review for Thinking About Art, Edmund Burke Feldman, Prentice Hall, Englewood Cliffs, NJ, 1985
Imaginal preaching: an archetypal perspective
Reviewed Book: Wallace, James A. Imaginal preaching: an archetypal perspective. Mahwah, NJ: Paulist Pr, 1995
Liturgies of the Future: The Process and Methods of Inculturation
Reviewed Book: Chupungco, Anscar J. Liturgies of the Future: The Process and Methods of Inculturation. Mahwah, NJ: Paulist Press, 1989
The Covenant Never Revoked: Biblical Reflections on a Christian-Jewish Dialogue
Reviewed Book: Lohfink, Norbert. The Covenant Never Revoked: Biblical Reflections on a Christian-Jewish Dialogue. Mahwah, NJ: Paulist Press, 1991
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