71,214 research outputs found
Optimality in Goal-Dependent Analysis of Sharing
We face the problems of correctness, optimality and precision for the static
analysis of logic programs, using the theory of abstract interpretation. We
propose a framework with a denotational, goal-dependent semantics equipped with
two unification operators for forward unification (calling a procedure) and
backward unification (returning from a procedure). The latter is implemented
through a matching operation. Our proposal clarifies and unifies many different
frameworks and ideas on static analysis of logic programming in a single,
formal setting. On the abstract side, we focus on the domain Sharing by Jacobs
and Langen and provide the best correct approximation of all the primitive
semantic operators, namely, projection, renaming, forward and backward
unification. We show that the abstract unification operators are strictly more
precise than those in the literature defined over the same abstract domain. In
some cases, our operators are more precise than those developed for more
complex domains involving linearity and freeness.
To appear in Theory and Practice of Logic Programming (TPLP
A Resource Intensive Traffic-Aware Scheme for Cluster-based Energy Conservation in Wireless Devices
Wireless traffic that is destined for a certain device in a network, can be
exploited in order to minimize the availability and delay trade-offs, and
mitigate the Energy consumption. The Energy Conservation (EC) mechanism can be
node-centric by considering the traversed nodal traffic in order to prolong the
network lifetime. This work describes a quantitative traffic-based approach
where a clustered Sleep-Proxy mechanism takes place in order to enable each
node to sleep according to the time duration of the active traffic that each
node expects and experiences. Sleep-proxies within the clusters are created
according to pairwise active-time comparison, where each node expects during
the active periods, a requested traffic. For resource availability and recovery
purposes, the caching mechanism takes place in case where the node for which
the traffic is destined is not available. The proposed scheme uses Role-based
nodes which are assigned to manipulate the traffic in a cluster, through the
time-oriented backward difference traffic evaluation scheme. Simulation study
is carried out for the proposed backward estimation scheme and the
effectiveness of the end-to-end EC mechanism taking into account a number of
metrics and measures for the effects while incrementing the sleep time duration
under the proposed framework. Comparative simulation results show that the
proposed scheme could be applied to infrastructure-less systems, providing
energy-efficient resource exchange with significant minimization in the power
consumption of each device.Comment: 6 pages, 8 figures, To appear in the proceedings of IEEE 14th
International Conference on High Performance Computing and Communications
(HPCC-2012) of the Third International Workshop on Wireless Networks and
Multimedia (WNM-2012), 25-27 June 2012, Liverpool, U
International investment positions and risk sharing: an empirical analysis on the coordinated portfolio investment survey
By using data from all available waves of the IMF Coordinated Portfolio In- vestment Surveys, we explore the dynamics of the determinants of cross portfolio investments. The main aim of our analysis, however, is to understand whether a diversification motive can also be found, among the various determinants. We find strong evidence that, indeed, the correlation between the idiosyncratic components of gdp growth, as well as the correlation between stock returns between pair of coun- tries, that we consider as proxies for diversification, are relevant to explain bilateral portfolio holdings, when unobserved heterogeneity is properly taken into account, by means of a fixed effect, panel estimation (where the fixed effects refer to pair of countries, rather than countries in isolation). Interestingly, the same results, cannot be retrieved from cross section estimations. It also turns out that the diversification motive is less relevant, if at all, in choosing whether or not to invest in a particular area
Forward Exponential Performances: Pricing and Optimal Risk Sharing
In a Markovian stochastic volatility model, we consider financial agents
whose investment criteria are modelled by forward exponential performance
processes. The problem of contingent claim indifference valuation is first
addressed and a number of properties are proved and discussed. Special
attention is given to the comparison between the forward exponential and the
backward exponential utility indifference valuation. In addition, we construct
the problem of optimal risk sharing in this forward setting and solve it when
the agents' forward performance criteria are exponential.Comment: 29 page
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