46,948 research outputs found
On the Proximity Factors of Lattice Reduction-Aided Decoding
Lattice reduction-aided decoding features reduced decoding complexity and
near-optimum performance in multi-input multi-output communications. In this
paper, a quantitative analysis of lattice reduction-aided decoding is
presented. To this aim, the proximity factors are defined to measure the
worst-case losses in distances relative to closest point search (in an infinite
lattice). Upper bounds on the proximity factors are derived, which are
functions of the dimension of the lattice alone. The study is then extended
to the dual-basis reduction. It is found that the bounds for dual basis
reduction may be smaller. Reasonably good bounds are derived in many cases. The
constant bounds on proximity factors not only imply the same diversity order in
fading channels, but also relate the error probabilities of (infinite) lattice
decoding and lattice reduction-aided decoding.Comment: remove redundant figure
The nilpotent variety of is irreducible
In the late 1980s, Premet conjectured that the nilpotent variety of any
finite dimensional restricted Lie algebra over an algebraically closed field of
characteristic is irreducible. This conjecture remains open, but it is
known to hold for a large class of simple restricted Lie algebras, e.g. for Lie
algebras of connected reductive algebraic groups, and for Cartan series
and . In this paper, with the assumption that , we confirm this
conjecture for the minimal -envelope of the Zassenhaus algebra
for all .Comment: 18 pages, Lemma 3.1 in [v2] is deleted and a few mistakes are
correcte
Finiteness of cohomology groups of stacks of shtukas as modules over Hecke algebras, and applications
In this paper we prove that the cohomology groups with compact support of
stacks of shtukas are modules of finite type over a Hecke algebra. As an
application, we extend the construction of excursion operators, defined by V.
Lafforgue on the space of cuspidal automorphic forms, to the space of
automorphic forms with compact support. This gives the Langlands
parametrization for some quotient spaces of the latter, which is compatible
with the constant term morphism.Comment: published versio
Optimizing the RVB state on a triangular lattice: Presence of the long-range order
We present a Schwinger-boson approach for the RVB state of the spin-1/2
Heisenberg antiferromagnet on a triangular lattice. It is shown that Gutzwiller
projection of the mean-field state that includes both antiferromagnetic and
ferromagnetic decouplings leads to optimizing the RVB pair amplitudes within a
self-consistent approximation. The resulting state yields, by Monte Carlo
simulations, energies and spin-spin correlations in excellent agreement with
the exact diagonalization result on finite lattices (up to 36 sites). We
conclude that the optimized RVB wavefunction possesses a long-range
three-sublattice order.Comment: 11 pages, plain LATEX (no local report #
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