1,247 research outputs found
On sets of integers which contain no three terms in geometric progression
The problem of looking for subsets of the natural numbers which contain no
3-term arithmetic progressions has a rich history. Roth's theorem famously
shows that any such subset cannot have positive upper density. In contrast,
Rankin in 1960 suggested looking at subsets without three-term geometric
progressions, and constructed such a subset with density about 0.719. More
recently, several authors have found upper bounds for the upper density of such
sets. We significantly improve upon these bounds, and demonstrate a method of
constructing sets with a greater upper density than Rankin's set. This
construction is optimal in the sense that our method gives a way of effectively
computing the greatest possible upper density of a geometric-progression-free
set. We also show that geometric progressions in Z/nZ behave more like Roth's
theorem in that one cannot take any fixed positive proportion of the integers
modulo a sufficiently large value of n while avoiding geometric progressions.Comment: 16 page
Liberty’s Honors Manager, Mrs. Laura Kline: Service to Lord and Family
Meet the Manager of LU Honors\u27 Program, Mrs. Laura Kline
SPATIAL MARKET INTEGRATION: DEFINITION, THEORY, AND EVIDENCE
A point-space model of interregional trade is used to define market integration and to explore its implications for modeling spatial price relationships. This analysis indicates that spatial prices are related nonlinearly, contrary to much of the work on spatial price analysis which uses linear models. As an empirical example, corn market integration along the Mississippi River is examined during the Midwest flood of 1993. Higher transport costs during this period significantly reduced the extent of integration and thereby decreased excess demand shock transference across regions.Agribusiness,
Physiology of chimpanzees in orbit. Part 1: Scientific Report
Major achievements and accomplishments are reported for the Physiology of Chimpanzees in Orbit Program. Scientific studies relate to behavior and physiology, and engineering studies cover telemetry, behavioral training, systems tests, life support subsystems, and program plan
An Exploration of Market Pricing Efficiency: The Dairy Options Pilot Program
Put options have been recommended as a substitute for price support programs (Gardner, 1977), and subsidized option purchases have received some support in lieu of subsidized insurance programs. Put options are an interesting alternative to price supports because their market-determined price levels allow for flexibility and adjustments to relevant current and expected market conditions. One difficulty with the use of put options as a substitute for commodity price supports is the relative thinness of these options markets for some commodities. Market thinness is defined here as the absence of traders willing to take the necessary opposite position in the market in lieu of a relatively large price premium, particularly for a large number of contracts. We explore empirically how a thin market responds when trading increases as a result of a subsidized put option program. USDA initiated the Dairy Options Pilot Program (DOPP) in 1999 in an effort to provide dairy producers with real-world experiences trading options (Vandeveer et al., 2003). Subsequently, additional rounds of DOPP occurred to give more producers a chance to participate. In total, over 1,300 producers bought 6,500 milk put option contracts through the DOPP program from 1999 to 2002. In contrast, over this four-year period total put options traded at the CME milk futures market totaled over 36,000 contracts. This, the volume from the DOPP program represented a fairly large share of total trading activity in the dairy put options market. An interesting feature of the subsidized milk options program is that dairy farmers may have made relatively little use of commodities markets due to the long-standing dairy price support programs. If this is the case, many of the dairy farmers making use of this subsidized options purchase program would have been relatively uniformed traders. Although DOPP may have increased trading volume, market performance may or may not have been enhanced due to the relative unfamiliarity with options trading by these dairy producers. We define a measure for observed options pricing efficiency using Black's formula in our study of the DOPP program, and statistically evaluate the size of the "error" in options pricing. We find that DOPP trades occurred at statistically significantly higher prices than did other trades, that DOPP volume had a price-reducing effect on other options trades, and that some brokers with large DOPP volume filled these orders at relatively large prices.Marketing,
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