To any finite collection of smooth real vector fields Xj in R we associate a metric in the phase space T ∗Rn. The relation between the asymptotic behavior of this metric and hypoellipticity of ∑ X j , in the smooth, real analytic, and Gevrey categories, is explored. To Professor P. Lelong, on the occasion of his 85th birthday.

The collective behavior of economic agents during speculative episodes provides the foundations of this book. Such moments are marked by a special atmosphere of optimism and confidence in the future, which permeates the entire market and society as a whole. Exuberance, ebullience, and bullish are some of the expressions used to describe the up-going phase; whilst words such as uncertainty, fear...

In the context of flexible exchange rates, Milton Friedman proposed that speculation must exert a stabilising influence upon prices to remain profitable. This generated a wealth of predominantly theoretical research into the behaviour of speculators, for which the results seem to depend critically upon the assumptions. Such theoretical models need to be tested against empirical evidence to dete...

Several studies of speculative execution based on values have reported promising performance potential. However, virtually all microarchitectures in these studies were described in an ambiguous manner, mainly due to the lack of formalization that defines the effects of value–speculation on a microarchitecture. In particular, the manifestations of value–speculation on the latency of microarchite...

Agricultural land prices in many developed countries rose and then fell dramatically over a relatively short period of time in the late 1970s and early 1980s. Most of the models in the literature that describe the dynamic behaviour of agricultural land prices suggest that these sharp price movements were not completely due to market fundamentals. Many attribute part of this price volatility to ...

On July 25 1978, Louise Joy Brown, the first baby to be conceived outside the human body, was born. Her birth made headlines as it showed that in vitro fertilisation techniques could provide a cure for infertility, helping couples who otherwise could not conceive. But Louise Joy Brown’s birthday represents a singular moment in the history of humankind for another reason: science had brought the...

The Harvard community has made this article openly available. Please share how this access benefits you. Your story matters. It is sometimes asserted that rational speculative activity must result in more stable prices because speculators buy when prices are low and sell when they are high. This is incorrect. Speculators buy when the chances of price appreciation are high, selling when the chan...

In the last few years negation and speculation scope classification systems have been developed successfully, most of them using machine–learning approaches. In this paper we present a competitive system that finds the scope of negation and speculation in sentences for English by means of syntactic dependency analysis without using machine–learning. A greedy algorithm first detects the cues (le...