This work analyzes correlations arising from quantum systems subject to sequential projective measurements certify that the system in question has a dimension greater than somed. We refine previous known methods and show two can be certified scenarios which are considerably simpler ones presented before and, fo...

We prove a version of B ezout's theorem for non-commutative analogues of the projective spaces P n. 0. Introduction Throughout we work over an algebraically closed eld k. We establish a version of B ezout's Theorem for non-commutative projective spaces, quantum P n s for short. If Y is a quantum P n then the alternating sum of the dimension of the Ext-groups gives a bilinear form : K 0 (Y) K 0 ...

The Macaulayfication of a Noetherian scheme X is a birational proper morphism Y → X such that Y is a CohenMacaulay scheme. Of course, a desingularization is a Macaulayfication and Hironaka gave a desingularization of arbitrary algebraic variety over a field of characteristic 0. In 1978 Faltings gave a Macaulayfication of a quasi-projective scheme whose nonCohen-Macaulay locus is of dimension 0 ...

(Algebra) It’s a complex projective manifold C of dimension one. As such, it has a field of rational functions K(C) of transcendence degree one over the field C of scalars. The curve can be recovered from the field as the set of discrete valuation rings of K/C, which has the “natural” structure of a projective manifold. There is a canonical line bundle ωC , whose degree captures the genus via d...

Abstract. We introduce a method to determine if n-dimensional smooth subvarieties of an ambient space of dimension at most 2n − 2 inherit the Picard group from the ambient space (as it happens when the ambient space is a projective space, according to results of Barth and Larsen). As an application, we give an affirmative answer (up to some mild natural numerical conditions) when the ambient sp...

We show that the Hodge and pole order filtrations are different for a sufficiently general singular projective hypersurface of degree 3 or 4 if the dimension of the projective space is at least 5 or 3 respectively. We then prove a variant of Wotzlaw’s formula for the Hodge filtration in case the singular points of a hypersurface are ordinary double points and their images by the e-fold Veronese...

Let k be a field and G a finite group. By analogy with the theory of phantom maps in topology, a map f : M → N between kG-modules is said to be phantom if its restriction to every finitely generated submodule of M factors through a projective module. We investigate the relationships between the theory of phantom maps, the algebraic theory of purity, and Rickard’s idempotent modules. In general,...