distinct categories of individuals, each with a unique natural history and etiology: A small group engages in antisocial behavior of 1 sort or another at every life stage, whereas a larger group is antisocial only during adolescence. According to the theory of life-course-persistent antisocial behavior

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Information retrieval (IR) has changed considerably in the last years with the expansion of the Web (World Wide Web) and the advent of modern and inexpensive graphical user interfaces and mass storage devices. As a result, traditional IR textbooks have become quite out-of-date which has led

"He who can, does. He who cannot, teaches. “ 1 don't know in what fit of pique George Bernard Shaw wrote that infamous aphorism, words that have plagued members of the teach-ing profession for nearly a century. They are found in "Maxims for Revolutionists, " an appendix to his play Man and Superman. "He who can, does. He who cannot, teaches" is a calamitous insult to our profes-sion, yet one readily repeated even by teachers. More worrisome, its philosophy often appears to under-lie the policies concerning the occu-pation and activities of teaching. Where did such a demeaning im-age of the teacher's capacities ori-ginate? How long have we been bur-dened by assumptions of ignorance and ineptitude within the teaching corps? Is Shaw to be treated as the last word on what teachers know and don't know, or do and can't do? Yesterday's Examinations We begin our inquiry into concep-tions of teacher knowledge with the tests for teachers that were used in this country during the last century This paper was a Presidential Ad-dress at the 1985 annual meeting of

The Internet presents numerous sources of useful information---telephone directories, product catalogs, stock quotes, weather forecasts, etc. Recently, many systems have been built that automatically gather and manipulate such information on a user's behalf. However, these resources

covered include: the choice of cost function and robustness; numerical optimization including sparse Newton methods, linearly convergent approximations, updating and recursive methods; gauge (datum) invariance; and quality control. The theory is developed for general robust cost functions rather than

A constraint that actions can depend on observations only through a communication channel with finite Shannon capacity is shown to be able to play a role very similar to that of a signal extraction problem or an adjustment cost in standard control problems. The resulting theory looks enough like

for economists to consider happiness. The first is economic policy. At the micro-level, it is often impossible to make a Pareto-optimal proposal, because a social action entails costs for some individuals. Hence an evaluation of the net effects, in terms of individual utilities, is needed. On an aggregate level

, like the propositions in a text. Dlogrammotlc representations ore indexed by location in a plane. Dio-grommatic representations also typically display information that is only implicit in sententiol representations and that therefore has to be computed, sometimes at great cost, to make it explicit

in terms of intentional dependency relationships among agents. Agents depend on each other for goals to be achieved, tasks to be performed, and resources to be furnished. Agents are intentional in that they have desires and wants, and strategic in that they are concerned about opportunities