The maximum likelihood detection of multiple input multiple output (MIMO) spatial multiplexing systems is strongly limited by its complexity. We propose that a quantized version of this problem permits the multiplications involved in the numerous calculations of Euclidean distances to be replaced by the use of a small look-up table storing all the exact possible distance components in each dime...

— In this paper we explicitly compute the first Vafa-Witten bound for a two-dimensional torus, namely the best uniform upper bound for the first eigenvalue of the family of twisted (by arbitrary vector potentials) Dirac operators on a flat two-torus. Starting with an arbitrary flat metric we give either an exact answer or a precise algorithm for producing an answer. As a by-product we develop a...

We construct examples of compact homogeneous Riemannian manifolds admitting an invariant Bismut connection that is Ricci flat and non-flat, proving in this way the generalized Alekseevsky–Kimelfeld theorem does not hold. The classification spaces dimension $5$ also provided. Moreover, we investigate with non-trivial third Betti number, point out other possible ways to manifolds. Finally, since ...

We consider Bel–Robinson-like higher derivative conserved two-index tensors H µν in simple matter models, following a recently suggested Maxwell field version. In flat space, we show that they are essentially equivalent to the true stress-tensors. In curved Ricci-flat backgrounds it is possible to redefine H µν so as to overcome non-commutativity of covariant derivatives, and maintain conservat...

Abstract In this article, we give a proof for positive mass theorem (PMT) of asymptotically flat manifolds with arbitrary ends when the dimension is no greater than seven. As an application, also show PMT locally Euclidean necessary incompressible conditions.

Recently, Yekutieli introduced projective dimension, injective dimension and flat of DG-modules by generalizing the characterization ordinary modules vanishing Ext or Tor-groups. In this paper, we introduce a DG-version projective, resolution for over connective DG-algebra which are different from known resolutions. An important feature these resolutions is that, roughly speaking, “length” give...

In this paper‎, ‎we study the class of rings in which every $P$-flat‎ ‎ideal is flat and which will be called $PFF$-rings‎. ‎In particular‎, ‎Von Neumann regular rings‎, ‎hereditary rings‎, ‎semi-hereditary ring‎, ‎PID and arithmetical rings are examples of $PFF$-rings‎. ‎In the context domain‎, ‎this notion coincide with‎ ‎Pr"{u}fer domain‎. ‎We provide necessary and sufficient conditions for‎...

in 2001, s. bulman-fleming et al. initiated the study of three flatness properties (weakly kernel flat, principally weakly kernel flat, translation kernel flat) of right acts $a_{s}$ over a monoid $s$ that can be described by means of when the functor $a_{s} otimes -$ preserves pullbacks. in this paper, we extend these results to$s$-posets and present equivalent descriptions of weakly kernel po...