Book Review: May I Have a Word With You?

A book review of Steven Kahan\u27s May I Have A Word With You

Higgs-mass predictions

A compilation of Higgs-mass predictions is proposedComment: This is the last version. Only addition: today's update by Kahana & Kahan

Random perturbation of low rank matrices: Improving classical bounds

Matrix perturbation inequalities, such as Weyl's theorem (concerning the singular values) and the Davis-Kahan theorem (concerning the singular vectors), play essential roles in quantitative science; in particular, these bounds have found application in data analysis as well as related areas of engineering and computer science. In many situations, the perturbation is assumed to be random, and the original matrix has certain structural properties (such as having low rank). We show that, in this scenario, classical perturbation results, such as Weyl and Davis-Kahan, can be improved significantly. We believe many of our new bounds are close to optimal and also discuss some applications.Comment: 28 pages, 1 figure. Updated introduction and reference

Kahan on Mistakes

In Ignorance of Law Is an Excuse - but Only for the Virtuous, Professor Dan Kahan reconciles what I had thought was an irreconcilable body of law. To be sure, imposing order on whether and when mistakes of law should pass as responsibility-evading accountsof untoward actions is far from light work. Yet Kahan somehow pulls it off in just twenty-seven pages. In addition to acknowledging the importance of Professor Kahan\u27s essay, I write here to point out if not correct what might have been two oversights in his view of the meaning and operation of mistakes. First, Kahan never acknowledges that the legal moralism he endorses has long governed when mistakes of fact - which bear at least a family resemblance to mistakes of law - can excuse us from responsibility for what we have done. Second, the real power and demands of Kahan\u27s essay are only hinted at. While the implication of his thesis - that law is suffused with morality and... the making of moral judgments \u27 - is profound, Kahan stakes out no moral positions. Kahan certainly is free to consign to courts the task of establishing criteria for evaluating whether, for example, possessing firearms, failing to pay taxes, illegally transporting wildlife, and failing to report campaign contributions are matters of morality as well as of law. Still (and this may be morepersonal than dialectical), I felt deprived by his refusal to answer what, at least to my mind, had provided the occasion for his essay: Is it moral to obey the law? Immoral to break it