Grounding-mechanical explanation

Characterization of a form of explanation involving grounding on the model of mechanistic causal explanation

Priority monism

Argument that priority monism is best understood as being a contingent thesis

On spectral and numerical properties of random butterfly matrices

Spectral and numerical properties of classes of random orthogonal butterfly matrices, as introduced by Parker (1995), are discussed, including the uniformity of eigenvalue distributions. These matrices are important because the matrix-vector product with an $N$-dimensional vector can be performed in $O(N \log N)$ operations. And in the simplest situation, these random matrices coincide with Haar measure on a subgroup of the orthogonal group. We discuss other implications in the context of randomized linear algebra.Comment: Fixed a few typos and added some additional comment

Prioritizing platonism

Discussion of atomistic and monistic theses about abstract reality

Smoothed Analysis for the Conjugate Gradient Algorithm

The purpose of this paper is to establish bounds on the rate of convergence of the conjugate gradient algorithm when the underlying matrix is a random positive definite perturbation of a deterministic positive definite matrix. We estimate all finite moments of a natural halting time when the random perturbation is drawn from the Laguerre unitary ensemble in a critical scaling regime explored in Deift et al. (2016). These estimates are used to analyze the expected iteration count in the framework of smoothed analysis, introduced by Spielman and Teng (2001). The rigorous results are compared with numerical calculations in several cases of interest

Demand for and Regulation of Cardiac Services

Efforts to regionalize cardiac services can increase access costs for patients. This study quantifies this trade off by estimating the effects of changes in the regulation of hospital services on treatments and outcomes. A demand model for surgery services is specified in which heart attack victims form expectations of the need for and productivity of surgery in their choice of hospital and treatment. The results indicate that mortality is relatively insensitive to moderate changes in policy: changes in travel costs and volume offset one another. Despite similar health outcomes, the competing policies have different implications for taxpayers.heart attack, Medicare, dynamic discrete choice estimation