Iterated Differential Forms IV: C-Spectral Sequence

For the multiple differential algebra of iterated differential forms (see math.DG/0605113 and math.DG/0609287) on a diffiety (O,C) an analogue of C-spectral sequence is constructed. The first term of it is naturally interpreted as the algebra of secondary iterated differential forms on (O,C). This allows to develop secondary tensor analysis on generic diffieties, some simplest elements of which are sketched here. The presented here general theory will be specified to infinite jet spaces and infinitely prolonged PDEs in subsequent notes.Comment: 8 pages, submitted to Math. Dok

Domains in Infinite Jets: C-Spectral Sequence

Domains in infinite jets present the simplest class of diffieties with boundary. In this note some basic elements of geometry of these domains are introduced and an analogue of the C-spectral sequence in this context is studied. This, in particular, allows cohomological interpretation and analysis of initial data, boundary conditions, etc, for general partial differential equations and of transversality conditions in calculus of variations. This kind applications and extensions to arbitrary diffieties will be considered in subsequent publications.Comment: 7 pages; no proofs give

Iterated Differential Forms I: Tensors

We interpret tensors on a smooth manifold M as differential forms over a graded commutative algebra called the algebra of iterated differential forms over M. This allows us to put standard tensor calculus in a new differentially closed context and, in particular, enriches it with new natural operations. Applications will be considered in subsequent notes.Comment: 9 pages, extended version of the published note Dokl. Math. 73, n. 2 (2006) 16

Iterated Differential Forms II: Riemannian Geometry Revisited

A natural extension of Riemannian geometry to a much wider context is presented on the basis of the iterated differential form formalism developed in math.DG/0605113 and an application to general relativity is given.Comment: 12 pages, extended version of the published note Dokl. Math. 73, n. 2 (2006) 18

Vinogradov's mean value theorem via efficient congruencing

We obtain estimates for Vinogradov's integral which for the first time approach those conjectured to be the best possible. Several applications of these new bounds are provided. In particular, the conjectured asymptotic formula in Waring's problem holds for sums of s kth powers of natural numbers whenever s is at least 2k^2+2k-3

Destructive Effects of Constructive Ambiguity in Risky Times

Unclear bailout policy, underinvestment and calls for bankers? responsibility are some of the observations from the recent financial crisis. The paper explains underinvestment as an inefficient equilibrium. Under ambiguous bailout policy agents suffer from a lack of information with regards to the insolvency resolution methods. Beliefs of bankers regarding whether an insolvent bank is liquidated, may differ from those of depositors even if bankers and depositors possess absolutely symmetric information about the economy. It is shown that such an asymmetry in beliefs results in underinvestment if the investment climate is characterized by high aggregate risk. The paper suggests policy implications aimed at the reduction of anxiety of agents and at aligning their beliefs to restore efficiency