Government policy response to war-expenditure shocks

A theory of government policy determination, based on intertemporal distortion-smoothing and limited commitment, matches the set of stylized facts of U.S. wartime policy.Government spending policy ; War - Economic aspects ; War finance

Policy and welfare effects of within-period commitment

I study the implications of different institutional frameworks for the conduct of fiscal policy, under the assumption that the government cannot commit to future policy choices. The environments analyzed vary on whether the government is endowed with the ability to commit to beginning-of-period policy announcements or not. If it cannot, then there are two variants, depending on which actions private agents take before observing the government’s policy choice. How the three possible cases rank in terms of tax rates and welfare varies substantially with the economy’s fundamentals and whether depreciation is tax deductible or not. More generally, I find that regimes with higher tax rates do not necessarily imply lower welfare. I also find that making depreciation not tax-deductible typically involves a welfare loss. Within the context of the environments studied in this paper, I find that there are only small gains from modifying the way fiscal policy is conducted in modern developed economies. Furthermore, some reforms may lead to large welfare losses.Fiscal policy ; Welfare ; Equilibrium (Economics)

Government policy in monetary economies

I study how the general and specific details of a micro founded monetary framework affect the determination of policy when the government has limited commitment. The conduct of policy depends on the interaction between the incentive to smooth distortions intertemporally and a time-consistency problem. In equilibrium, fiscal and monetary policies are distortionary, but long-run policy is not afflicted by time-consistency problems. Policy variables in specific applications of the general framework react similarly to variations in fundamentals. Nevertheless, resolving certain environment frictions affect long-run policy significantly. The response of government policy to aggregate shocks is qualitatively similar across the studied model variants. However, there are significant quantitative differences in the response of government policy to productivity shocks, mainly due to the idiosyncratic behavior of the money demand. Environments with no trading frictions display the best fit to post-war U.S. data.Economic policy

Government Policy in Monetary Economies

I study how the specific details of a micro founded monetary economy affect the determination of government policy. I consider three variants of the Lagos-Wright monetary framework: a benchmark were all markets are competitive; a case which allows for financial intermediaries; and a case with trading frictions. Although intitutions/frictions are shown to have a significant structural impact in the determination of policy, the calibrated artificial economies are observationally equivalent in steady state. The policy response to aggregate shocks is qualitatively similar in the variants considered. However, there are significant quantitative differences in the response of government policy to productivity shocks, mainly due to the idiosyncratic behavior of money demand. The variants with no trading frictions display the best fit to U.S. post-war data.government policy; lack of commitment; financial intermediation; trading frictions; micro founded models of money

Period Color and Amplitude Color relations for MACHO project LMC RR Lyraes

In this paper, we analyze period color and amplitude color relations at minimum, mean and maximum $V$ band light for 6391 RRab stars in the Large Magellanic Cloud obtained by the MACHO project. Specifically, we find that color and amplitude are nearly independent of period at minimum light but that there exists a definite relation between period and color and amplitude and color at maximum light. These two properties are easily explained by the application of the Stefan Boltzmann law and the interaction of the photosphere and hydrogen ionization front at minimum light. When we examine the slope of the period color relation as a function of phase, we find that the slope varies significantly with phase and is small for a wide range of phases around minimum light. This suggests that another factor that needs to be considered when trying to understand RR Lyrae observed properties is their behavior at different phases during a pulsation cycle.Comment: Sumitted for publication to MNRAS Letter

On spectral types of semialgebraic sets

In this work we prove that a semialgebraic set $M\subset{\mathbb R}^m$ is determined (up to a semialgebraic homeomorphism) by its ring ${\mathcal S}(M)$ of (continuous) semialgebraic functions while its ring ${\mathcal S}^*(M)$ of (continuous) bounded semialgebraic functions only determines $M$ besides a distinguished finite subset $\eta(M)\subset M$. In addition it holds that the rings ${\mathcal S}(M)$ and ${\mathcal S}^*(M)$ are isomorphic if and only if $M$ is compact. On the other hand, their respective maximal spectra $\beta_s M$ and $\beta_s^* M$ endowed with the Zariski topology are always homeomorphic and topologically classify a `large piece' of $M$. The proof of this fact requires a careful analysis of the points of the remainder $\partial M:=\beta_s^* M\setminus M$ associated with formal paths.Comment: 22 page

Investigating Evaluation Measures in Ant Colony Algorithms for Learning Decision Tree Classifiers

Ant-Tree-Miner is a decision tree induction algorithm that is based on the Ant Colony Optimization (ACO) meta- heuristic. Ant-Tree-Miner-M is a recently introduced extension of Ant-Tree-Miner that learns multi-tree classification models. A multi-tree model consists of multiple decision trees, one for each class value, where each class-based decision tree is responsible for discriminating between its class value and all other values present in the class domain (one vs. all). In this paper, we investigate the use of 10 different classification quality evaluation measures in Ant-Tree-Miner-M, which are used for both candidate model evaluation and model pruning. Our experimental results, using 40 popular benchmark datasets, identify several quality functions that substantially improve on the simple Accuracy quality function that was previously used in Ant-Tree-Miner-M