Quantitative bounds are presented for the superlinear convergence of the MINRES method of Paige and Saunders [SIAM J. Numer. Anal., 1975] for the solution of sparse linear systems Ax = b, with A symmetric and indefinite. It is shown that the superlinear convergence is observed as soon as the harmonic Ritz values approximate well the eigenvalues of A that are either closest to zero or farthest f...

We consider the harmonic superspaces associated to SU(2, 2/N) superconformal algebras. For arbitrary N , we show that massless representations, other than the chiral ones, correspond to [N2 ] “elementary” ultrashort analytic superfields whose first component is a scalar in the k antisymmetric irrep of SU(N) (k = 1 . . . [N2 ]) with top spin Jtop = ( N 2 − k 2 , 0 ) . For N = 2n we analyze UIR’s...

I consider Lagrangians which depend nonlocally in time but in such a way that there is no mixing between times differing by more than some finite value ∆t. By considering these systems as the limits of ever higher derivative theories I obtain a canonical formalism in which the coordinates are the dynamical variable from t to t+∆t. A simple formula for the conjugate momenta is derived in the sam...

We derive and analyze new boundary element (BE) based finite element discretizations of potential-type, Helmholtz and Maxwell equations on arbitrary polygonal and polyhedral meshes. The starting point of this discretization technique is the symmetric BE Domain Decomposition Method (DDM), where the subdomains are the finite elements. This can be interpreted as a local Trefftz method that uses PD...

The matrix elements of the quadrupole variables and canonic conjugate momenta emerging from collective nuclear models are calculated within an SU(1, 1)× O(5) basis. Using a harmonic oscillator implementation of the SU(1, 1) degree of freedom, one can show that the matrix elements of the quadrupole phonon creation and annihilation operators can be calculated in a pure algebraic way, making use o...

An efficient multiresolution method to compute global conformal structures of nonzero genus triangle meshes is introduced. The homology, cohomology groups of meshes are computed explicitly, then a basis of harmonic one forms and a basis of holomorphic one forms are constructed. A progressive mesh is generated to represent the original surface at different resolutions. The conformal structure is...

The Einstein-Podolsky-Rosen (EPR) paradox, which was formulated to argue for the incompleteness of quantum mechanics, has since metamorphosed into a resource for quantum information. The EPR entanglement describes the strength of linear correlations between two objects in terms of a pair of conjugate observables in relation to the Heisenberg uncertainty limit. We propose that entanglement can b...

The generalization of p-frame in Banach spaces is considered in this paper. The concepts of an $tilde{X}$-frame and a system conjugate to $tilde{X}$-frame were introduced. Analogues of the results on the existence of conjugate system were obtained. The stability of $tilde{X}$-frame having a conjugate system is studied.

If H denotes the classical Hilbert transform and Hu(x) = v(x), then the functions u(x) and v(x) are the values on the real axis of a pair of conjugate functions, harmonic in the upper half-plane. This note gives a generalization of the above concepts in which the Laplace equation Deltau = 0 is replaced by the Yukawa equation Deltau = mu(2)u and in which the Cauchy-Riemann equations have a corre...

We introduce the dual Koenigs lattices, which are the integrable discrete analogues of conjugate nets with equal tangential invariants, and we find the corresponding reduction of the fundamental transformation. We also introduce the notion of discrete normal congruences. Finally, considering quadrilateral lattices ”with equal tangential invariants” which allow for harmonic normal congruences we...