Constraint-based evaluation of sequential procedures

Constraining the operation of an agent requires knowledge of the restrictions to physical and temporal capabilities of that agent, as well as an inherent understanding of the desires being processed by that agent. Usually a set of constraints are available that must be adhered to in order to foster safe operations. In the worst case, violation of a constraint may be cause to terminate operation. If the agent is carrying out a plan, then a method for predicting the agent's desires, and therefore possible constraint violations, is required. The conceptualization of constraint-based reasoning used herein assumes that a system knows how to select a constraint for application as well as how to apply that constraint once it is selected. The application of constraint-based reasoning for evaluating certain kinds of plans known as sequential procedures is discussed. By decomposing these plans, it is possible to apply context dependent constraints in production system fashion without incorporating knowledge of the original planning process

Do Asymmetric Central Bank Preferences Help Explain Observed Inflation Outcomes?

When the central banker’s loss function is asymmetric, changes in the volatility of inflation and/or unemployment affect equilibrium inflation. This suggests that changing macroeconomic volatilities may be an important driving force behind trends in observed inflation. Previous evidence, which has offered support for this idea, suffers from a spurious regression problem. Once this problem is controlled for, the evidence suggests that the volatility of unemployment does not help explain inflation outcomes. There is some evidence of a relationship between inflation and its volatility, but overall the data does not support the view that changing economic volatility, as filtered through asymmetric central bank preferences, is an important driver of inflation trends.Inflation, Monetary Policy, Asymmetric Loss Function.

Introduction: The effectiveness of impact assessment instruments

The global application of impact assessment instruments to achieve a variety of policy integration goals (e.g. the mainstreaming of environmental, gender or economic efficiency concerns) continues to proliferate. These instruments represent important components of contemporary political governance and hence are an important locus for applied research. This special issue of Impact Assessment and Project Appraisal critically examines 'state-of-the-art' knowledge and understanding of the effectiveness of impact assessment instruments. Six articles explore this subject from a variety of orientations (in terms of theoretical versus empirical emphasis, policy integration concerns, contributors' beliefs and framing etc.). Individually and cumulatively, these articles make a powerful contribution to learning about the 'thorny' issue of effectiveness and its implications for the theory and practice of impact assessment

Do Asymmetric Central Bank Preferences Help Explain Observed Inflation Outcomes?

Recent theoretical work shows that changes in the volatility of inflation and/or unemployment affect equilibrium inflation outcomes when the central banker's loss function is asymmetric. We show that previous evidence offered in support of the proposition that the volatility of unemployment helps explain inflation outcomes suffers from a spurious regression problem. Once this problem is controlled for, the evidence suggests that the volatility of unemployment does not help explain inflation outcomes. There is some evidence of a relationship between inflation and its volatility, but the data is not strongly supportive of the view that asymmetric central bank preferences are an important driver of inflation.inflation; monetary policy; asymmetric loss

Testing Commitment Models of Monetary Policy: Evidence from OECD Economies

Inflation rates in a number of OECD follow a common trend over the past four decades: inflation starts out low in the 1960s, rises for a time before peaking in the 1970s or early 1980s, and then falls back to initial levels. This similarity in the behavior of trend inflation suggests that any explanation of long run inflation trends ought to apply across OECD countries. Ireland (1999) shows that a simple time inconsistency model of monetary policy, modified to allow for a time-varying NAIRU, can explain long run trends in U.S. inflation. In this paper we show that this result cannot serve as an explanation of the common trend in OECD inflation, as it fits the data only in the U.S.. We investigate two important variants of the hypothesis: i) that time inconsistency was an important component of central bank behavior in earlier decades, but has become less significant in recent years, and ii) that time inconsistency problems drive U.S. inflation, which affects inflation rates in other countries as a result of central bankers' attempts to manage nominal exchange rate movements vis a vis the U.S. dollar. We find that the first hypothesis fits the data no better than the baseline model. We find some support for the international spillovers version of the model, but the behavior of non-U.S. central bankers with respect to domestic unemployment rates is not well described by the time inconsistency mechanism.monetary policy; inflation; time incosistency

In vivo characterization of hippocampal electrophysiological processes in the heterozygous Pten knockout model of autism

While cognitive deficits have been described in the heterozygous Pten (+/-) KO mouse model of autism, little work has been done to demonstrate how corresponding in vitro physiological alterations in this model may underpin these cognitive deficits in vivo. As Pten KO (+/-) is known to alter electrophysiological characteristics of neurons in vitro, this study measures the in vivo electrophysiological characteristics of CA1 interneurons, pyramidal cells, and place cells which may underlie the spatial cognitive deficits seen in the model. Four transgenic conditional heterozygous Pten+/loxPloxP;Gfap-cre mice (HetPten) and four homozygous Pten littermate control mice were used in this study. This transgene drives cre expression and excision of the Pten gene in hippocampal granule cells of the dentate gyrus, and neurons in CA2 and CA1, but not astrocytes. In vivo local field potentials and single cell recordings were made in CA1 of each mouse during an open field foraging task in two distinct arenas. HetPten mice were found to have increased interneuron and pyramidal cell firing rates. In addition, place cells demonstrated abnormal properties including increased out-of-field firing rates, an increased number of fields, and trends towards larger field sizes that were less stable in comparison to controls. HetPten mice had slower CA1 fast gamma oscillations and more variable speed/theta oscillation correlations. Behaviorally, there were weak trends towards decreased motor output compared to controls. These data suggest that the electrophysiological alterations due to Pten KO (+/-) in mouse hippocampal neurons lead to hyperactivation of CA1 interneurons, pyramidal cells, and place cells

Using philosophy to improve the coherence and interoperability of applications ontologies: A field report on the collaboration of IFOMIS and L&C

The collaboration of Language and Computing nv (L&C) and the Institute for Formal Ontology and Medical Information Science (IFOMIS) is guided by the hypothesis that quality constraints on ontologies for software ap-plication purposes closely parallel the constraints salient to the design of sound philosophical theories. The extent of this parallel has been poorly appreciated in the informatics community, and it turns out that importing the benefits of phi-losophical insight and methodology into application domains yields a variety of improvements. L&C’s LinKBase® is one of the world’s largest medical domain ontologies. Its current primary use pertains to natural language processing ap-plications, but it also supports intelligent navigation through a range of struc-tured medical and bioinformatics information resources, such as SNOMED-CT, Swiss-Prot, and the Gene Ontology (GO). In this report we discuss how and why philosophical methods improve both the internal coherence of LinKBase®, and its capacity to serve as a translation hub, improving the interoperability of the ontologies through which it navigates

Analyzing spacecraft configurations through specialization and default reasoning

For an intelligent system to describe a real-world situation using as few statements as possible, it is necessary to make inferences based on observed data and to incorporate general knowledge of the reasoning domain into the description. These reasoning processes must reduce several levels of specific descriptions into only those few that most precisely describe the situation. Moreover, the system must be able to generate descriptions in the absence of data, as instructed by certain rules of inference. The deductions applied by the system, then, generate a high-level description from the low-level evidence provided by the real and default data sources. An implementation of these ideas in a real-world situation is described. The application concerns evaluation of Space Shuttle electromechanical system configurations by console operators in the Mission Control Center. A production system provides the reasoning mechanism through which the default assignments and specializations occur. Examples are provided within this domain for each type of inference, and the suitability is discussed of each toward achieving the goal of describing a situation in the fewest statements possible. Finally, several enhancements are suggested that will further increase the intelligence of similar spacecraft monitoring applications

The Almost Ideal and Translog Demand Systems

This chapter reviews the specification and application of the Deaton and Muellbauer (1980) Almost Ideal Demand System (AIDS) and the Christensen, Jorgensen, and Lau (1975) tranlog (TL) demand system. In so doing we examine various refinements to these models, including ways of incorporating demographic effects, methods by which curvature conditions can be imposed, and issues associated with incorporating structural change and seasonal effects. We also review methods for adjusting for autocorrelation in the model's residuals. A set of empirical examples for the AIDS and a the log TL version of the translog based on historical meat price and consumption data for the United States are also presented.Almost ideal demand system, Autocorrelation, Curvature, Meat Demand, Translog