Tight frames can be characterized as those frames which possess optimal numerical stability properties. In this paper, we consider the question of modifying a general frame to generate a tight frame by rescaling its frame vectors; a process which can also be regarded as perfect preconditioning of a frame by a diagonal operator. A frame is called scalable, if such a diagonal operator exists. We ...

Abstract. In this paper, we study certain Virasoro frames for lattice vertex operator algebras and their Z2-orbifolds using linear codes over Z4. We also compute the corresponding frame stabilizer from the view point of binary codes and Z4-codes. As an application, we determine the frame stabilizers of several Virasoro frames of the vertex operator algebra VE8 and the moonshine vertex operator ...

We construct a typed hierarchy of effective algebraic domains with totality of height the first recursively Mahlo ordinal. The hierarchy is based on the empty type and the domains for singleton, boolean values and natural numbers, and it is closed under dependent sums and pro-ducts of effectivly parameterised families of types, and under universes closed under a very general universe operator.

We present results about minimization of convex functionals defined over a finite set of vectors in a finite dimensional Hilbert space, that extend several known results for the Benedetto-Fickus frame potential. Our approach depends on majorization techniques. We also consider some perturbation problems, where a positive perturbation of the frame operator of a set of vectors is realized as the ...

some necessary and sufficient conditions are given for the existence of a g-positive (g-repositive) solution to adjointable operator equations $ax=c,axa^{left( astright) }=c$ and $axb=c$ over hilbert $c^{ast}$-modules, respectively. moreover, the expressions of these general g-positive (g-repositive) solutions are also derived. some of the findings of this paper extend some known results in the...

‎in this paper‎, ‎first we develop the duality concept for $g$-bessel sequences‎ ‎and bessel fusion sequences in hilbert spaces‎. ‎we obtain some results about dual‎, ‎pseudo-dual ‎and approximate dual of frames and fusion frames‎. ‎we also expand every $g$-bessel ‎sequence to a frame by summing some elements‎. ‎we define the restricted isometry property for ‎$g$-frames and generalize some resu...