In the Relevance Feedback (RF) task the user is directly involved in the search process: given an initial set of results, he specifies if they are relevant or not to the achievement of his information goal. In the TREC 2009 RF track the first five documents retrieved by the baseline systems were judged by the assessors and then used as evidence for the RF algorithms to be tested. The specific a...

‎the global fom and gmres algorithms are among the effective‎ ‎methods to solve sylvester matrix equations‎. ‎in this paper‎, ‎we‎ ‎study these algorithms in the case that the coefficient matrices‎ ‎are real symmetric (real symmetric positive definite) and extract‎ ‎two cg-type algorithms for solving generalized sylvester matrix‎ ‎equations‎. ‎the proposed methods are iterative projection metho...

Let M be a smooth manifold of positive dimension n equipped with a smooth density dμM. Let A be a polyhomogeneous elliptic pseudo-differential operator of positive order m onM which is symmetric for the L scalar product defined by dμM. For each L > 0, the space UL = ⊕ λ≤LKer(A− λId) is a finite dimensional subspace of C∞(M). Let ΠL be the spectral projector onto UL. Given s ∈ R, we compute the ...

The problem of estimating the location of one or more coherent point scatterers from the time-reversal matrix as computed from backscattered narrow or broadband multi-static data is investigated. For the case of homogeneous backgrounds it is shown that under very weak conditions and as long as the number of sensor elements exceeds the number of scatterers the time reversal matrix has a rank equ...

We study the space of all extensions of a real hyperplane arrangement by a new pseudo-hyperplane, and, more generally, of an oriented matroid by a new element. The question whether this space has the homotopy type of a sphere is a special case of the “Generalized Baues Problem” of Billera, Kapranov & Sturmfels, via the Bohne-Dress Theorem on zonotopal tilings. We prove that the extension space ...