向谁求助？

就在贝卡和乐天蚁想方设法向食人花求饶的时候,有植物从旁边经过。对了。请他们来帮帮忙!可是。向谁求助比较好呢？     

胖警官的求助

正约翰和福尔摩西出门去观测天文,今天天气并不好,很难看到满意的星象。他们怀着遗憾的心情,半夜四点多钟才回到家里。刚到楼梯口就发现了坐在家门口正在打鼾的胖大叔。约翰一下子就认出了他:这不是隔壁镇的胖警官大叔吗?胖警官一下子惊醒,抬起头,看见他们很激动:哎呀你们终于回来了!我等你们好久了。福尔摩西抓起袖子将它们盖过手腕,夜里有些冷了。他很疑惑:你等我们干什么?我有个重要的案件,需要寻求福尔摩东的     

Fermats ?ad?quare? – und kein Ende?

In his papers on the determination of maxima and minima and on the calculation of tangents Pierre Fermat uses two different Latin verbs, ?quare and ad?quare, which do not differ semantically but are used by him obviously in different meanings. While ?quabitur is used unambiguously in the sense of “is equal” the meaning of ad?quabitur is disputed by the experts since Tannery’s French translation (Œuvres complètes de Fermat, Vol. III, 1896). Herbert Breger (Arch. Hist. Exact Sci. 46, 193–219, (1994), p. 197 f), for instance, holds the view that Fermat used the word ad?quare in the sense of “to put equal” and adds: In a mathematical context, the only difference between “?quare” and “ad?quare” (if there is any) seems to be that the latter gives more stress on the fact that the equality is achieved. In contrast to this Michael Mahoney holds the thesis that ad?quare describes a counterfactual equality (Mahoney, M.S.: Fermat, Pierre de. In: Dictionary of Scientific Biography, vol. IV (1971), p. 569) or a pseudo-equality (Mahoney, M.S.: The Mathematical Career of Pierre de Fermat (1601–1665), (1973), p. 164), whatever that may mean. This viewpoint has been taken up again recently by Enrico Giusti (Ann. Fac. Sci. Toulouse, Math. (6), 18 fascicule spécial, 59–85 (2009)) in order to bring arguments to bear against Breger. In contrast to these (and other) authors, I show that Fermat makes a subtle logical distinction between the words ?quare and ad?quare. The same distinction is made by Nicolas Bourbaki introducing his ?théorie égalitaire?. Notwithstanding: both verbs stand for a ?relation d’égalité?. On this premiss, I describe—using six selected examples—that Fermat’s “method” may be justified right down to the last detail, even from the view of today’s mathematical knowledge.     

多讲?少讲?不讲?

近日读到著名经济学家张五常回忆其大学老师的一篇文章 ,引起我的一些思考 .文章说 ,老师让学生花了四个星期的时间自己去研究问题解决的办法 ,但学生们都找不到办法 .第五个星期 ,老师进入课室 ,“在五十分钟内 ,他如长江大河 ,滔滔不绝 ,使我听得呆了 .……”作者说 ,“假若没有经过那四个星期去想 ,我不会在五十分钟之内被老师说服的吧” .虽然故事讲的是大学教学 ,但是 ,我想我们的中学教学中 ,不也存在一个“讲”与“不讲” ,“多讲”与“少讲”的问题吗 ?在“满堂灌”的授课方式受到批评后 ,不少老师又都在培养学生能力的口号下祭起了…     

Re-use? Is this re-use?

An initiative such as the Intergeo project has the clear mission to allow many teachers to gain easy access to resources that can support their teaching practice when using them. Re-use then appears when the sole usage is insufficient and needs adaptations to the specific context. This paper investigates the common practices of re-use in computer science literature, describes how it was implemented in the i2geo platform, and how the actual usage of the platform shows that the definition we first envisioned and that is widespread is short sighted. Following the observations of the practices, generalizations of the notion of re-use are proposed.     

O?shore ?oating wind turbine and its dynamic problems?

Green energy sources and ocean wind power are plentiful in deep sea. More and more o?shore wind power plants are constructed in the deep water over hundred meters below the surface. While o?shore ?oating wind turbine system is working, wind turbine, ?oating foundation, and mooring system a?ect each other with wind, waves, and currents acting on them. Various o?shore ?oating wind turbine systems and the encoun-tered environmental loads are brie?y reviewed and discussed. It is di?cult and crucial to comprehensively analyze the aerodynamic-hydrodynamic-service system-structure un-der the coupling e?ect of o?shore ?oating wind turbine system. The environmental ?ow ?eld, structure scale, and rational applications of theories and approaches should be well considered in advance.     

Beitr?ge zur St?rungstheorie

Ohne ZusammenfassungHerrn Professor Dr. H.Kneser zum 60. Geburtstag gewidmet     

A Bernstein type theorem in ? × ? n

In this paper, as suitable application of the so-called Omori-Yau generalized maximum principle, we obtain a Bernstein type theorem concerning to complete hypersurfaces immersed with constant mean curvature in the product space ℝ × ℍ ⁿ . Furthermore, we treat the case that such hypersurfaces are vertical graphs.     

How Close is the Sample Covariance Matrix to?the?Actual Covariance Matrix?

Given a probability distribution in ? ⁿ with general (nonwhite) covariance, a classical estimator of the covariance matrix is the sample covariance matrix obtained from a sample of N independent points. What is the optimal sample size N=N(n) that guarantees estimation with a fixed accuracy in the operator norm? Suppose that the distribution is supported in a centered Euclidean ball of radius $O(\sqrt{n})$ . We conjecture that the optimal sample size is N=O(n) for all distributions with finite fourth moment, and we prove this up to an iterated logarithmic factor. This problem is motivated by the optimal theorem of Rudelson (J. Funct. Anal. 164:60?C72, 1999), which states that N=O(nlog?n) for distributions with finite second moment, and a recent result of Adamczak et al. (J. Am. Math. Soc. 234:535?C561, 2010), which guarantees that N=O(n) for subexponential distributions.     

What lifts?

As is well known, idempotents in any ring R lift modulo any nil idea I. That is, if a ? R and (a₂-a) ? I there is an i ? I with (a + i)²-- (a + i) = 0. An idempotent is a zero of the polynomial x ²?x ², and a nil element satisfies x ⁿfor some n. Seen this way, lifting occurs in considerable generality We assume R has a unit, and handle the non-unital case at the end of this paper.     

陷阱有多深?

正青青草原的春天来了,灰太狼一家外出踏青。小灰灰忙着抓蝴蝶,正玩得起劲,突然听到爸爸妈妈的求救声。呀!爸爸妈妈掉进陷阱里了。一家人想了很多办法,又是跳又是爬,但是陷阱太深了,灰太狼和红太狼怎么都出不来。小灰灰急得快要哭出来了。突然,他想起了羊村里的朋友们,就急忙去羊村求救。羊村的羊羊们来救援了。为了教育一下灰太狼,喜羊羊想出了一个主意,说:"灰太狼先生,我这儿有一根绳子,把绳子放到一口井里,单根放到井底,井外会多出15米。对折后再放入,会多出井口1米。你知道这口井有多深,绳子有多长吗?"