6,040 research outputs found
Optimal control of elliptic equations with positive measures
Optimal control problems without control costs in general do not possess
solutions due to the lack of coercivity. However, unilateral constraints
together with the assumption of existence of strictly positive solutions of a
pre-adjoint state equation, are sufficient to obtain existence of optimal
solutions in the space of Radon measures. Optimality conditions for these
generalized minimizers can be obtained using Fenchel duality, which requires a
non-standard perturbation approach if the control-to-observation mapping is not
continuous (e.g., for Neumann boundary control in three dimensions). Combining
a conforming discretization of the measure space with a semismooth Newton
method allows the numerical solution of the optimal control problem
What is the Minimal Systemic Risk in Financial Exposure Networks?
Management of systemic risk in financial markets is traditionally associated
with setting (higher) capital requirements for market participants. There are
indications that while equity ratios have been increased massively since the
financial crisis, systemic risk levels might not have lowered, but even
increased. It has been shown that systemic risk is to a large extent related to
the underlying network topology of financial exposures. A natural question
arising is how much systemic risk can be eliminated by optimally rearranging
these networks and without increasing capital requirements. Overlapping
portfolios with minimized systemic risk which provide the same market
functionality as empirical ones have been studied by [pichler2018]. Here we
propose a similar method for direct exposure networks, and apply it to
cross-sectional interbank loan networks, consisting of 10 quarterly
observations of the Austrian interbank market. We show that the suggested
framework rearranges the network topology, such that systemic risk is reduced
by a factor of approximately 3.5, and leaves the relevant economic features of
the optimized network and its agents unchanged. The presented optimization
procedure is not intended to actually re-configure interbank markets, but to
demonstrate the huge potential for systemic risk management through rearranging
exposure networks, in contrast to increasing capital requirements that were
shown to have only marginal effects on systemic risk [poledna2017]. Ways to
actually incentivize a self-organized formation toward optimal network
configurations were introduced in [thurner2013] and [poledna2016]. For
regulatory policies concerning financial market stability the knowledge of
minimal systemic risk for a given economic environment can serve as a benchmark
for monitoring actual systemic risk in markets.Comment: 25 page
The EU Emissions Trading System and Climate Policy towards 2050: Real incentives to reduce emissions and drive innovation? CEPS Special Reports, 12 January 2011
With the EU Emissions Trading System (ETS) now entering in its seventh year of operation, this report takes stock of the largest multi-sector greenhouse gas trading scheme in the world. It reviews the experiences of the pilot phase from 2005-07, assesses the adjustments introduced in the second phase (2008-12) and looks ahead to the radical changes that will come into effect in the third phase starting in 2013. The assessment is based on a literature review of recently published ex-post analyses and ex-ante studies and draws as well on our own calculations. It investigates the main controversies surrounding the EU ETS, such as its environmental effectiveness, economic rents, windfall profits and fairness, the role of CDM and JI and its impact of on industrial competitiveness. It also evaluates the schemeâs ability to promote innovation and low-carbon technology deployment. Finally, the study addresses the fundamental question of whether the ETS has lived up to its promise to âpromote reductions of greenhouse gas emissions in a cost-effective and economically efficient mannerâ, and if not, what are the prospects of its doing so in the future and what additional changes will be required
Sketched Answer Set Programming
Answer Set Programming (ASP) is a powerful modeling formalism for
combinatorial problems. However, writing ASP models is not trivial. We propose
a novel method, called Sketched Answer Set Programming (SkASP), aiming at
supporting the user in resolving this issue. The user writes an ASP program
while marking uncertain parts open with question marks. In addition, the user
provides a number of positive and negative examples of the desired program
behaviour. The sketched model is rewritten into another ASP program, which is
solved by traditional methods. As a result, the user obtains a functional and
reusable ASP program modelling her problem. We evaluate our approach on 21 well
known puzzles and combinatorial problems inspired by Karp's 21 NP-complete
problems and demonstrate a use-case for a database application based on ASP.Comment: 15 pages, 11 figures; to appear in ICTAI 201
THE ROLE OF CROSS-CLASS ALLIANCES AND ELITES IN COORDINATED EMPLOYMENT RELATIONS IN DENMARK. CES Open Forum Series 2018-2019, September 4, 2018
Explanations for coordination between labor and capital in Northern Europe continue to
cause debate among scholars of comparative political economy. On one hand, power
resource scholars argue that strong trade unions promoting equality are necessary for
coordination. On the other hand, employer-centered theories argue that employers are the
primary actors in promoting coordination due to the comparative advantages stemming
from coordination. To inform this debate, we study the case of Denmark by combining a
unique database of 5.000 elite affiliations with 80 stakeholder interviews spanning a
decade. We argue that trade union power resources are necessary for coordination.
However, only when certain segments of labor can forge powerful alliances with key
employers for the economy will coordination persist. The network analysis identifies a
powerful cross-class alliance between trade unions and employer associations in
manufacturing. Interviews with stakeholders show that coordination in industrial relations
and related institutional spheres such as education and industrial policies serves this
allianceâs interests in safeguarding international competitiveness of manufacturing.
However, intra-class allegiances ensure that the alliance constantly has to consider the
interests of outsider organizations
Time evolution of a toy semiholographic glasma
We extend our previous study of a toy model for coupling classical Yang-Mills
equations for describing overoccupied gluons at the saturation scale with a
strongly coupled infrared sector modeled by AdS/CFT. Including propagating
modes in the bulk we find that the Yang-Mills sector loses its initial energy
to a growing black hole in the gravity dual such that there is a conserved
energy-momentum tensor for the total system while entropy grows monotonically.
This involves a numerical AdS simulation with a backreacted boundary source far
from equilibrium.Comment: 17 pages, 7 figures, v2: minor changes in section 3 and
acknowledgement
From Violence to Witness via Reason and Faith : The Interreligious Message of Pope Benedict XVI
This article examines the message of Pope Benedict XVI to representatives of other religions, especially Muslims, using the popeâs interreligious addresses as the main source material. The main topics surveyed are the peaceful nature of religion, the relationship between faith and reason, and common service or interreligious witness. These are interconnected, for Benedict is convinced that religiously motivated violence is contrary to the essence of religion, irrational, and damaging to the common cause of the religions against radical ecularism. The difficulty arises in declaring a priori, based on Enlightenment convictions, that âgenuine religionâ is nonviolent at heart, without discussing the authoritative sources of each religion. It is striking that Benedict XVI never quotes the Qurâan in his speeches to Muslims. The appeals to reason, conscience, and human nature attempt to settle the matter on a level preceding faith, but the popeâs Augustinian-Bonaventurian vision requires that reason be illumined by faith and revelation. This framework, used interreligiously, as the pope does, cuts both ways. Who or what decides, in the face of a violent instance of ârevelationâ, whether faith is to be purified by reason, or reason elevated by faith? Benedict XVI provides a strong impetus to those who agree with him and food for thought to all who are open to dialogue, but more needs to be done in order to âargue credibly and realistically against religiously motivated violenceâ.Peer reviewe
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