3,550 research outputs found
Unusual square roots in the ghost-free theory of massive gravity
A crucial building block of the ghost free massive gravity is the square root
function of a matrix. This is a problematic entity from the viewpoint of
existence and uniqueness properties. We accurately describe the freedom of
choosing a square root of a (non-degenerate) matrix. It has discrete and (in
special cases) continuous parts. When continuous freedom is present, the usual
perturbation theory in terms of matrices can be critically ill defined for some
choices of the square root. We consider the new formulation of massive and
bimetric gravity which deals directly with eigenvalues (in disguise of
elementary symmetric polynomials) instead of matrices. It allows for a
meaningful discussion of perturbation theory in such cases, even though certain
non-analytic features arise.Comment: 24 pages; minor changes, final versio
Social Cost of Carbon: What Do the Numbers Really Mean?
Social cost of carbon (SCC) is estimated by integrated assessment models
(IAM) and is widely used by government agencies to value climate policy
impacts. While there is an ongoing debate about obtained numerical estimates
and related uncertainties, little attention has been paid so far to the SCC
calculation method itself.
This work attempts to fill the gap by providing theoretical background and
economic interpretation of the SCC calculation approach implemented in the
open-source IAM DICE (Dynamic Integrated model of Climate and the Economy). Our
analysis indicates that the present calculation method provides an
approximation that might work pretty well in some cases, while in the other
cases the estimated value substantially (by the factor of four) deviates from
the "true" value. This deviation stems from the inability of the present
calculation method to catch the linkages between two key IAM's components --
complex interconnected systems -- climate and economy, both influenced by
emission abatement policies. Within the modeling framework of DICE, the
presently estimated SCC valuates policy-uncontrolled emissions against
economically unjustified consumption, which makes it irrelevant for application
in climate-economic policies and, therefore, calls for a replacement by a more
appropriate indicator.
An apparent SCC alternative, which can be employed for policy formulation is
the direct output of the DICE model -- the socially optimal marginal abatement
cost (SMAC), which corresponds to technological possibilities at optimal level
of carbon emissions abatement. In policy making, because of the previously
employed implicit approximation, great attention needs to be paid to the use of
SCC estimates obtained earlier
Competence–Based Support of Interaction between Business Network Members
In a complicated business network finding a supplier can be a very time consuming task. The
technology of competence management is aimed to support such kind of tasks. The paper presents an approach
to support interaction between business network members based on such technologies as competence
management and knowledge management. The conceptual models of the context-driven competence
management system and production network member competence profile are described. The usage of the
competence management system is illustrated via an example from automotive industry
Shadow prices and optimal cost in economic applications
Shadow prices are well understood and are widely used in economic
applications. However, there are limits to where shadow prices can be applied
assuming their natural interpretation and the fact that they reflect the first
order optimality conditions (FOC). In this paper, we present a simple ad-hoc
example demonstrating that marginal cost associated with exercising an optimal
control may exceed the respective cost estimated from a ratio of shadow prices.
Moreover, such cost estimation through shadow prices is arbitrary and depends
on a particular (mathematically equivalent) formulation of the optimization
problem. These facts render a ratio of shadow prices irrelevant to estimation
of optimal marginal cost. The provided illustrative optimization problem links
to a similar approach of calculating social cost of carbon (SCC) in the widely
used dynamic integrated model of climate and the economy (DICE)
Economic Aspects of Maritime Transport Development
In the article on the basis of the analysis of features of activity of the marine transport of Russia in 2010-2015, dynamics of its key economic indicators are defined tendencies of development of the marine transport in general and its structural components in the fast-changing environmental conditions
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