发帖数: 1 | 1 WHY IDO?
http://idolinguo.org.uk/whyido.htm
NOTE: Because of the difficulty of showing Esperanto's special accented
letters, where a letter which in Esperanto should carry a circumflex it is
shown here followed by a circumflex (^), and where the letter 'u' should
carry a breve it is followed by a tilde (~).
The idea of using a constructed language as a medium of international
communication - not replacing existing languages but supplementing them - is
far from new. The first such language to ach... 阅读全帖 |
|
发帖数: 1 | 2 HOW IDO WORKS
https://www.youtube.com/watch?v=BTVtaB2nU8w&list=
PL0eUjNQs8Qf9SK214nZuK41ffkxvKeA0A
http://idolinguo.org.uk/works.htm
INTERNATIONAL UNDERSTANDING
The idea of an international language is simply to enable people who have no
other language in common to understand one another. Ido (pronounced "ee-doh
") was developed by linguists and scientists over a number of years. It is
the most practical language to be invented, and its usability has been
demonstrated many times, both in writing... 阅读全帖 |
|
o*****l
发帖数: 734 | 3 耶鲁教授马丁 施瓦茨（刚从弗吉尼亚大学搬到耶鲁）的论文：愚蠢在科研中的重要性
论点：施瓦茨教授的一个朋友从研究生退学去了哈佛法学院。原因是科研每天都让他觉
得自己很愚蠢，需要做些别的事情。
（我是十分同意这个观点。科研，尤其是生命科学这个活是非一般心里素质的人可以干
的，因为每天都会和失败打交道。长时间的失败磨灭了你的信心，意志和前进的勇气。
很多人选择了退出，很多剩下的人留下来并非心里过硬，而是生活所迫，所谓的科研对
于很多人来说不是理想，而是谋生的手段。）
施瓦茨教授也是这样感觉的，只不过是吐啊吐啊，吐习惯成自然就好了
如何解决这个问题呢？（我也不知道，看看施瓦茨教授的观点吧，虽然觉得他有点站着
说话不腰疼的感觉）
原文： http://jcs.biologists.org/content/121/11/1771.full
The importance of stupidity in scientific research
Martin A. Schwartz
+Author Affiliations
Department of Microbiology, UVA Health S... 阅读全帖 |
|
o*****l
发帖数: 734 | 4 耶鲁教授马丁 施瓦茨（刚从弗吉尼亚大学搬到耶鲁）的论文：愚蠢在科研中的重要性
论点：施瓦茨教授的一个朋友从研究生退学去了哈佛法学院。原因是科研每天都让他觉
得自己很愚蠢，需要做些别的事情。
（我是十分同意这个观点。科研，尤其是生命科学这个活是非一般心里素质的人可以干
的，因为每天都会和失败打交道。长时间的失败磨灭了你的信心，意志和前进的勇气。
很多人选择了退出，很多剩下的人留下来并非心里过硬，而是生活所迫，所谓的科研对
于很多人来说不是理想，而是谋生的手段。）
施瓦茨教授也是这样感觉的，只不过是吐啊吐啊，吐习惯成自然就好了
如何解决这个问题呢？（我也不知道，看看施瓦茨教授的观点吧，虽然觉得他有点站着
说话不腰疼的感觉）
原文： http://jcs.biologists.org/content/121/11/1771.full
The importance of stupidity in scientific research
Martin A. Schwartz
+Author Affiliations
Department of Microbiology, UVA Health S... 阅读全帖 |
|
S**I
发帖数: 15689 | 5 根据wiki：
There are no other known Fermat primes Fn with n > 4. However, little is
known about Fermat numbers with large n. In fact, each of the following is
an open problem:
Is Fn composite for all n > 4?
Are there infinitely many Fermat primes?
Are there infinitely many composite Fermat numbers?
你的这个数是Fermat number的一个特例，如果上述问题解决了，你的问题也就解决了
。当然，这可不是个简单的数学问题。 |
|
e***n
发帖数: 286 | 6 【 以下文字转载自 Quant 讨论区 】
发信人: erain (红花会大老板), 信区: Quant
标 题: 关于 American option pricing 问题的讨论
发信站: BBS 未名空间站 (Fri Jul 1 13:43:16 2011, 美东)
stock price S(t) follows the standard GBM process, 我们用 tao 来表示随机执行
期权的时刻，显然它是个stopping time,只依赖股价过去一直到 tao 这个时刻的历史
{S(u), 0 <= u <= tao}，美式期权的定价公式可以表达为一个 optimal stopping 的
问题，
V(S0) = max E[exp(-r*tao)*max{S(tao) - K, 0}]
0<= tao <=T or tao = +infinite
tao: stoppping time
这两天正和人争论一个小问题，我觉得，这里的公式可以去掉这个 max{} 函数，进一
步简化为
V(S0) = max E[exp(-r*tao) * (S(... 阅读全帖 |
|
w*****g
发帖数: 47 | 7
as long as there is some infinite cycle about knowledge, that is, not
everything is common knowledge, which in turn by itself is not common
knowledge, then it is hard to model this thought process. it is tricky becasue
of the infinitiness. as long as we assume the lack of common knowledge stops
at some point, then we can model it as uncertainty, and look back from that
point using Bayes rule. but if it is infinite, no matter what the lack of
common knowledge is about, we can not use Bayes rule |
|
z********u
发帖数: 30 | 8 在infinite horizon model, the chamley-jadd result tells that the optimal
capital taxation result is ZERO, but in OLD model, this result depends on
the utility functiont.
As we know, in circumstances of infinite horizon model, the distortion of
positive capital taxation means otherwise increasing consumption taxation
rate,
so, what is the intuition of failure of Chamley-judd result in OLD?
Thanks... |
|
G****n
发帖数: 145 | 9 Between trust and control: Developing confidence in partner cooperation in
alliances
[PDF] from cuny.edu…, BS Teng - Academy of management Review, 1998 - JSTOR
Strategic alliances have been recognized as arenas with potential for
opportunistic behavior
by partners. Hence, a firm needs to have an adequate level of confidence in
its partner's
cooperative behavior. In this article we examine the notion of confidence in
partner ...
Cited by 1749 - Related articles - BL Direct - All 9 versions
A reso... 阅读全帖 |
|
g****t
发帖数: 31659 | 10 那infinite loop加一些堆栈来处理中断优先级之类的东西，
可以算RTOS了吧？
interrupt priority不是靠你这个infinite loop实现的。 |
|
w********u
发帖数: 90 | 11 请问各位大神， 白噪声符合泊松分布（from wiki），那么其噪声功率应该是
和其signal 成正比。 那么电流为 I (A) 的白噪声功率应该是 sqrt（I）(A) in rms.
可是书上说 Inoise=sqrt（2*q*I*B）， B:bandwidth ，
怎么理解里面的2*B ? And, also does it mean at infinite bandwidth, noise is
also infinite?
困扰我很久的问题，谢谢! |
|
s******n
发帖数: 17 | 12 Q: 银河系到另外一个星系之间都有什么？空的？有恒星吗？
There are just my guess, don't take it seriously:
1. Mirror sites: galaxy after galaxy
2. Cyclic composition: like the surface of the earth
3. Singular point/boundary: there is a sudden boundary space where no material
exists
4. Infinite universe: endless
5. Finite yet expanding universe: as Einstein proposed
6. Infinite yet limited universe: as Hokins proposed |
|
k***n
发帖数: 383 | 13 我在做个题,
就是INSTANTANIOUS HEATING OF A SEMI-INFINITE PLATE.
一维的.在SCHUBERT AND TURCOTTE的GEODYNAMICS书里有.
半无限的平面.
at time t=0, temperature is T0 everywhere.
at time t>0, temperature at the boundary is Ts at y=0.
at y-> infinite, temperature is still T0.
这个问题是有解了,就是那个什么ERROR FUNCTION.
但我现在的问题是要把Ts弄成TIME DEPENTENT.
假设那是地核的话,外面导热,温度要降低,
我自己算的好象是
ln(Ts) = sqrt (kappa*t/pi).
不过我改的程序好象是给出ln(Ts) proportional to t (not t^(1/2)).
有没有高手看一看啊? |
|
c******m
发帖数: 599 | 14 Functional analysis is a branch of mathematics concerned with infinite-dimensional
vector spaces (mainly function spaces) and mappings between them. The spaces
may be of different, and possibly infinite, dimensions. These mappings are
called operators or, if the range is on the real line or in the complex
plane, functionals. |
|
w**a
发帖数: 1024 | 15 a cauchy sequence defined in matric space (X,d)
we know any cauchy sequence is bounded.
But this sequence also has infinite number of elements?
infinite bounded sequence can have NO accumulation point? Thanks. |
|
y**y
发帖数: 25 | 16 int\-infinit...+infinit\(exp(-x^2))dx=sqrt(pi)
有什么办法可以算出这个结果吗？ |
|
R******y
发帖数: 651 | 17 忘了具体说的是啥。大致是说一个complex variable z, 一个analytic function f(z)
如果 |z*f(z)| goes to zero as z goes to infinite, then infinite contour
integral f(z)dz is zero. 谁给回忆一下这个定理的名字是？印象里是叫做Jordan
theorem？ |
|
l*****0
发帖数: 179 | 18 infinite series Sn=(1/n) * (1-p)^(n-1)*p , what's the sum?
n from 1 to infinite,
0 |
|
j**********7
发帖数: 4 | 19 An interview question I met.
"Consider a matrix $J$. every eigenvalue of $J$ has positive real part.
Now let us consider infinite product of (1-J/n). Do you think this
infinite product converges? and how about the converge rate?"
Is there anyone can give some advice. thanks! |
|
s*x
发帖数: 3328 | 20 $S$ is co-infinite if complement of $S$ is a infinite set. I guess. |
|
l******o
发帖数: 1550 | 21 countable could be infinite, and usually infinite for my first impression |
|
f*******n
发帖数: 12623 | 22 Since the prime numbers are a subset of the natural numbers, the cardinality
of the set of prime numbers is no bigger than the cardinality of the
natural numbers (aleph_0). Now all you need to do is show that there are an
infinite number of prime numbers; then its cardinality must be no smaller
than aleph_0.
To show that there is an infinite number of prime numbers, assume that
opposite: there is a finite number of prime numbers. Multiply them together
and add 1; this new number is not divisible... 阅读全帖 |
|
r********9
发帖数: 1116 | 23 厚道啥，你看Goldston多酸
While the new sieve allowed Zhang to prove that there are infinitely many
prime pairs closer together than 70 million, it is unlikely that his methods
can be pushed as far as the twin primes conjecture, Goldston said.
Even with the strongest possible assumptions about the value of the level of
distribution, he said, the best result likely to emerge from the GPY method
would be that there are infinitely many prime pairs that differ by 16 or
less. |
|
g****t
发帖数: 31659 | 24 这个没觉得酸.基本上是学术判断.
而且这里的一些说法,张说不定也能同意.
厚道啥，你看Goldston多酸
While the new sieve allowed Zhang to prove that there are infinitely many
prime pairs closer together than 70 million, it is unlikely that his methods
can be pushed as far as the twin primes conjecture, Goldston said.
Even with the strongest possible assumptions about the value of the level of
distribution, he said, the best result likely to emerge from the GPY method
would be that there are infinitely many prime pairs that differ by 16 or
l... 阅读全帖 |
|
f*******i
发帖数: 1049 | 25 "There is some number N smaller than 70 million such
that there are infinitely many pairs of primes such that the gap between the
two numbers in each pair is N"
or equivalently
"There are infinitely many pairs of primes such that the gap between the two
primes in each pair is less than 70m" |
|
b*******n
发帖数: 5065 | 26
let k=infinite,
then
we get an infinite series of prime numbers,
it is contradict with the sparse distribution of prime number. |
|
b*******n
发帖数: 5065 | 27
let k=infinite,
then
we get an infinite series of prime numbers,
it is contradict with the sparse distribution of prime number. |
|
i****g
发帖数: 3896 | 28 北大怎么没宣传张？张的消息出来才一两天北大数院就发了新闻，北大主页放了三四天
，这是非常少见的。
http://pkunews.pku.edu.cn/xwzh/2013-05/15/content_272348.htm
数学科学学院校友张益唐在孪生素数研究方面取得重大突破
日期： 2013-05-15 信息来源： 数学科学学院
日前，Nature官网发布新闻：“无穷多素数成对存在的首次证明（First proof that
infinitely many prime numbers come in pairs）”，文章报道了北大数学科学学院
78级校友张益唐在孪生素数研究方面所取得的突破性进展，他证明了孪生素数猜想的一
个弱化形式。
众所周知，素数是指正因数只有1和本身的正整数。素数在整数里面是非常稀疏的。如
果我们将素数从小到大排一个次序，那么从概率上说，随着素数的增大，下一个素数离
上一个素数应该越来越远，而孪生素数猜想是说存在无穷多对素数，他们只相差2。例
如3和5，5和7，……，2,003,663,613 × 2^195,000- 1 和 2,003,663,613 × 2^... 阅读全帖 |
|
g****t
发帖数: 31659 | 29 能比得上施一工?
北大怎么没宣传张？张的消息出来才一两天北大数院就发了新闻，北大主页放了三四天
，这是非常少见的。
http://pkunews.pku.edu.cn/xwzh/2013-05/15/content_272348.htm
数学科学学院校友张益唐在孪生素数研究方面取得重大突破
日期： 2013-05-15 信息来源： 数学科学学院
日前，Nature官网发布新闻：“无穷多素数成对存在的首次证明（First proof that
infinitely many prime numbers come in pairs）”，文章报道了北大数学科学学院
78级校友张益唐在孪生素数研究方面所取得的突破性进展，他证明了孪生素数猜想的一
个弱化形式。
众所周知，素数是指正因数只有1和本身的正整数。素数在整数里面是非常稀疏的。如
果我们将素数从小到大排一个次序，那么从概率上说，随着素数的增大，下一个素数离
上一个素数应该越来越远，而孪生素数猜想是说存在无穷多对素数，他们只相差2。例
如3和5，5和7，……，2,003,663,613 × 2^195,000- 1 和 2,003,66... 阅读全帖 |
|
m****t
发帖数: 570 | 30 http://nautil.us/issue/5/fame/the-twin-prime-hero
The Twin Prime Hero
–Rags, riches, and fame in mathematics
MICHAEL SEGAL
Yitang “Tom” Zhang spent the seven years following the completion of his
Ph.D. in mathematics floating between Kentucky and Queens, working for a
chain of Subway restaurants, and doing odd accounting work. Now he is on a
lecture tour that includes stops at Harvard, Columbia, Caltech, and
Princeton, is fielding multiple professorship offers, and spends two hours a
day d... 阅读全帖 |
|
M****o
发帖数: 4860 | 31 December 02, 2013 9:53 AM
Press release
DURHAM — Yitang “Tom” Zhang, a lecturer in mathematics at the University
of New Hampshire, will receive the 2014 Frank Nelson Cole Prize in Number
Theory from the American Mathematical Society (AMS) and the 2013 Ostrowski
Prize.
Presented every three years, the Cole Prize recognizes an outstanding
research paper in number theory that has appeared in the preceding six years
. The prize will be awarded on Thursday, Jan. 16, 2014, at the AMS's Joint
Mathemati... 阅读全帖 |
|
s****b
发帖数: 2039 | 32 集合可以分为finite和infinite，infinite又可以分为countable和uncountable。
为什么自然数，有理数的集合是countable，而实数的集合是uncountable的？看了几本
书的解释，还是不敢苟同。实数虽然是连续的，但是如果我们在实数轴上每次任选一个
实数，这样第n次选的n是自然数，所选的是实数，以至无穷，实数不就和自然数一一对
应了吗？实数不就是countable了吗？
这个想法错在哪里呢？请懂的大牛指教一下吧。多谢！ |
|
M****o
发帖数: 4860 | 33 After Prime Proof, an Unlikely Star Rises
Two years ago, Yitang Zhang was virtually unknown. Now his surprise solution
to a major problem in number theory has catapulted him to mathematical
stardom. Where does he go from here?
https://www.quantamagazine.org/20150402-prime-proof-zhang-interview/
By: Thomas Lin
April 2, 2015
As a boy in Shanghai, China, Yitang Zhang believed he would someday solve a
great problem in mathematics. In 1964, at around the age of nine, he found a
proof of the Pythagore... 阅读全帖 |
|
d******s
发帖数: 180 | 34 [Distinguished Lecture] Small gaps between primes
Speaker: Professor Yitang Zhang, University of New Hampshire
Time: July 20, 2015 15:00-16:00
Venue: Lecture Hall, Jia Yi Bing Building, 82# Jing Chun Yuan
Abstract: The twin prime conjecture states that there are infinitely many
pairs of distinct primes which differ by 2. Until recently this conjecture
had seemed to be out of reach with current techniques. However, in 2013, the
author proved that there are infinitely many pairs of distinct primes... 阅读全帖 |
|
x********i
发帖数: 905 | 35 The Shaw Prize in Mathematical Sciences 2015 is awarded to Gerd Faltings,
Managing Director at Max Planck Institute for Mathematics in Bonn, Germany,
and Henryk Iwaniec, New Jersey Professor of Mathematics at Rutgers
University, USA, for their introduction and development of fundamental tools
in number theory, allowing them as well as others to resolve some
longstanding classical problems.
Number theory concerns whole numbers, prime numbers, and polynomial
equations involving them. The central p... 阅读全帖 |
|
d**o
发帖数: 79 | 36 1.G. F. Homicz and J. A. Lordi, ''A note on the radiative directivity
patterns
of duct acoustic modes,'' Journal of Sound and Vibration. 41, 283-290 1975
2.Y. ANDO. On the sound radiation from semi-infinite circular pipe of
certain wall thickness. Acustica, 1969. 22: p. 219-225.
3.M. Bernard and B. Denardo. Re-computation of ando's approximation of the
end correction for a radiating semi-infinite circular pipe. Acustica, 1996.
82(4): p. 670-671.
万分感谢！ 我邮箱：d****[email protected] |
|
R******y
发帖数: 651 | 37 【 以下文字转载自 Mathematics 讨论区 】
发信人: RICIIkey (昵称太短!), 信区: Mathematics
标 题: complex analysis 中的一个定理
发信站: BBS 未名空间站 (Sun Oct 21 21:27:30 2007)
忘了具体说的是啥。大致是说一个complex variable z, 一个analytic function f(z)
如果 |z*f(z)| goes to zero as z goes to infinite, then infinite contour
integral f(z)dz is zero. 谁给回忆一下这个定理的名字是？印象里是叫做Jordan
theorem？ |
|
z**********g
发帖数: 16 | 38 Discussing The Existence of “repulsion particle” And Its Significance
Zhuang Yiliong
Shanghai Institute of Science and Technology Management
Abstract:This report has advanced a assume about the existence of “
repellention” by a kind of new idea. Beginning with this, I have explained
more successfully some import theory questions in the area of the present
physics, cosmology and philosophy ect. At same time a few of new reasons
have been raised But this is only rough idea of physica... 阅读全帖 |
|
s*****n
发帖数: 209 | 39 I do not believe that reproduction right is a ``basic'' human right,
since this right depends on the social and environment resources and
constraints. If the Earth were infinitely large, and if the
environmental resource were infinitely abundant, then reproduction
right could be viewed as a basic right. However this is clearly not
the case.
Of course, one may argue that the current population in China
has not been critical and the land of China can still absorb any
uncontrolled new birth. Howeve |
|
y**y
发帖数: 25 | 40 【 以下文字转载自 Mathematics 讨论区 】
发信人: yuyy (yyy), 信区: Mathematics
标 题: Gaussian积分函数如何证明？
发信站: BBS 未名空间站 (Mon Aug 27 11:52:59 2007), 转信
int\-infinit...+infinit\(exp(-x^2))dx=sqrt(pi)
有什么办法可以算出这个结果吗？ |
|
b***k
发帖数: 2673 | 41 ☆─────────────────────────────────────☆
yuyy (yyy) 于 (Mon Aug 27 11:54:02 2007) 提到:
发信人: yuyy (yyy), 信区: Mathematics
标 题: Gaussian积分函数如何证明？
发信站: BBS 未名空间站 (Mon Aug 27 11:52:59 2007), 转信
int\-infinit...+infinit\(exp(-x^2))dx=sqrt(pi)
有什么办法可以算出这个结果吗？
☆─────────────────────────────────────☆
forrestarrow (linzhongxianjian+) 于 (Mon Aug 27 12:00:22 2007) 提到:
An easy way to think is integration of normal distribution function over -
infinty to + infinity should give you 1. You only need to m |
|
Q***5
发帖数: 994 | 42 Assuming r=0 is fine, not quite sure about infinite shorting: that means you
can borrow and keep a stock forever -- that is an arbitrage by itself: you
can sell the stock, enjoy the proceeds and don't have to worry about
returning the 'borrowed' stock.
【 from tradingGamma: 】
As I said, you need r=0 and allowing infinite shorting. Then for the lower
bound, you can short 1 share, this should allow you buy the option. You get
paid from the option to clear the short position on underline. |
|
j**********7
发帖数: 4 | 43 Consider a matrix $J$. every eigenvalue of $J$ has positive real part.
Now let us consider infinite product of (1-J/n). Does
infinite product converges? and how about the converge rate?
Is there anyone can give some advice? thanks! |
|
p*****k
发帖数: 318 | 44 not sure what exactly DuGu had in mind, but im guessing that
he wants the radii of these circles nonzero and bounded.
otherwise, e.g., the infinite str8 line R could be considered
as a circle with infinite radius:
(x-R)^2+y^2=R^2 with R->infty |
|
e***n
发帖数: 286 | 45 stock price S(t) follows the standard GBM process, 我们用 tao 来表示随机执行
期权的时刻，显然它是个stopping time,只依赖股价过去一直到 tao 这个时刻的历史
{S(u), 0 <= u <= tao}，美式期权的定价公式可以表达为一个 optimal stopping 的
问题，
V(S0) = max E[exp(-r*tao)*max{S(tao) - K, 0}]
tao belongs to [0,T] and {+infinite}
tao: stoppping time
这两天正和人争论一个小问题，我觉得，这里的公式可以去掉这个 max{} 函数，进一
步简化为
V(S0) = max E[exp(-r*tao) * (S(tao) - K)]
tao belongs to [0,T] and {+infinite}
tao: stoppping time
原因是，虽然 tao 是随机的，但是在任何你可以执行但是还没有执行期权的时刻 tao
，现在股价 S(tao... 阅读全帖 |
|
e***n
发帖数: 286 | 46 max 下的条件漏了 {infinite}，应该是
tao belongs to [0,T] plus {+infinite}
thanks |
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e***n
发帖数: 286 | 47 I know what you meant. Let's forget the American call without dividends,
which coincides with a European call.
Let's consider a general payoff function h like this:
h(x) = max{g(x), 0}, where g: R->R and g may takes any value
What I am trying to say is for American options with a payoff function h(x)
, the following two option pricing problems are equivalent. Both of them
give the same optimal exercising strategy
v(s) = max E{exp(-r*tau) * h(S(tau)) | S(0) = s}
tau belongs to [0, T] and {+... 阅读全帖 |
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z****t
发帖数: 78 | 48 I guess there are two easy ways to check if it is unstable or because of
human mistake: 1) make the infinite be 40 X strike; 2) make the underlying
price be strike and infinite be 2.5 X strike. |
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G**r
发帖数: 383 | 49 simple random walk:
P(S=0)=(b-10)/(b-a), when b->infinite, P(S=0)=1
Another way to think:
every state except s=0 is transient, [0] is absorbing. When t is infinite,
all the transient states go to [0] |
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h*****g
发帖数: 21 | 50 There are infinite cards numbered 1-5. You construct a deck. Someone guesses
a value and draws a card. If they guessed correctly, they get the value.
What composition of the deck minimizes their expected value？
题目没看懂， 一个deck是5张还是不限张数还是infinite的全部。5张的话是随便取五
张还是要一到五俱全？
要是把题目改为： here are five cards numbered 1-5. You construct a deck.
Someone guesses a value and draws a card. If they guessed correctly, they
get the value. What composition of the deck minimizes their expected value？
就简单了。 |
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