USA tops International Math Olympiad for first time in 21 years
washingtonpost.com
washingtonpost.com
It says:
Expii is a collection of free, interactive, explanations written by people from around the world
Interesting!
However, after being appointed to the national coach position, I realized that the USA would not be able to consistently deliver top results unless we lifted our mathematical level across a broad base. It seemed that technology could provide the solution to that problem, in the sense that it's possible to crowd-source the scripting of automatic virtual tutors, which can then be replayed (for free) on mobile devices throughout all regions, rich or poor. Thus, expii.com was born.
https://www.youtube.com/watch?v=11SdySDDrMk https://www.youtube.com/watch?v=t6WVbFIz43M
-- Po-Shen Loh
May I ask what your plan is for defending lessons against cranks, crusading ideologues, and the less-than-knowledgeable once it gets more adoption? Other collaborative projects such as Wikipedia have suffered as a result of this, but I noticed in your talk that your aim is to maintain "higher" quality than Wikipedia or even Stack Exchange and Quora. I'm curious how this can be accomplished once the user base expands beyond its initial network.
Congrats on this year's IMO result!
Wikipedia cannot do this because their objective is to cover 100 million topics (breadth), and so in-house moderation doesn't scale. Our objective is depth: we ultimately want to provide the absolute best free interactive lessons on every heavy-hitter topic in the world. :)
Thanks for your well-wishes!
He's really nice, and excited about improving math and science education. Expii could be called an "explorable explanations" Wikipedia[0]--one can write code (I think a subset of JS), embed videos etc in service of a better explanation.
I'm also fond of him because his office has an X server (or would that be X client?). How many startups actually use X??
[0] Just my two cents.
https://www.imo-official.org/participant_r.aspx?id=19624
Also, only 1 person got 3 perfect scores in the history of the event: Ciprian Manolescu (3 for 3 perfect) https://www.imo-official.org/participant_r.aspx?id=3789
[0] https://en.wikipedia.org/wiki/List_of_International_Mathemat...
http://www.quora.com/How-did-North-Korea-cheat-in-the-IMO-in...
Edit: have a read of this page. It shows that marking is not just a case of comparing the answer papers with a pre-prepared answer script. There is discussion and debate involved. http://www.imo-register.org.uk/2010-report.html
> Problem 4 was the second geometry problem, and so I led. We agreed four 7s straight away. The disputes were that I wanted a 7 for Luke Betts, and the co-ordinators were only offering 3 because they thought that there was a hole in his argument. On the other hand, they wanted to give Andrew Carlotti a 7 but I was only prepared to take 3. I explained to them the weakness in Carlotti’s argument, and they looked a little surprised. I asked them about the alleged weakness in Betts’s script, and I couldn’t understand what they were worried about. I suggested an overnight adjournment so that we could both make detailed preparations, and we met again the next day.
(I know that Thailand does have a series of math competition for kids starting at grade 3. This was started less than 20 years ago, which helps explain its much improved IMO performance over the last decade.)
Any Singaporeans care to explain?
Considering the fact that until 2011, we had only won ONE gold medal and rarely featured in the top 30.
But from 2011 onwards, have won 10 gold medals and have started to consistently appear in the top 10.
Background: Singaporean who once aspired into getting into the IMO team [this was circa <=2004]. But ended up with a crappy silver medal in the informatics olympiad. Now a washed up, recovering Perl hacker.
Perhaps there might have been special tracks and/or competitions to help nurture these kids and their peers for quite a while before the NUS high school was set up?
[0] https://www.imo-official.org/year_country_r.aspx?year=2015
[1] http://www.theguardian.com/science/2015/jul/15/us-wins-harde...
Notation: We borrow subscript and superscript notation from D. Knuth's TeX. So, a with a subscript j is written a_j.
Consider the simple graph, based just on typing, below. The graph shows the first four values of a specific sequence a_j. This sequence is a contradiction to claim of Problem 6.
In this graph, the values of j = 1, 2, ... are plotted on the horizontal axis with 1, 2, ..., and the values of the a_j are plotted on the vertical axis from 1 to 2015. We plot a value of a_j as just 'a'. Due to constraint (ii), we indicate by 'x' points that, due to prior values of a_j, cannot have an 'a'. So, the graph is:
2015
.
.
.
a_j .
5
4
3 a a
2 x x ...
1 axax
123456789
j
Then the first two terms of the sequence
a_j are: a_1 = 3
a_2 = 1
and generally for j = 1, 2, ..., a_j is: /
| 3 if j is odd
|
a_j = <
|
| 1 if j is even
\
Then for any positive integer b and j = 1,
2, ... (a_j - b) + (a_{j + 1} - b) >= 2
More generally for positive integers
m and k, sum_{j = m + 1}^{m + 2k} (a_j - b) >= 2 k
Then for any positive integer N, we can
set m = N and n = m + 2(1007^2) and get | sum_{j=m+1}^n (a_j - b) |
= sum_{j=m+1}^n (a_j - b)
= 2 (1007^2) > 1007^2
showing that the claim is false.The theorem seems entirely correct to me. You can prove it with these sub-steps:
(1) the set of all j + a_j is the set of nonnegative integers minus a finite number of gaps
(2) thus for large enough n you can express \sum_{j=1}^n (j + a_j) as a quadratic function of n, plus a residual term e(n) of magnitude at most 1007^2/2
(3) more precisely, \sum_{j=m+1}^n a_j = g (n-m) + e(n) - e(m) where g is the number of gaps in (1)
Then choosing b = g solves the problem.
Hope that helps.
Wouldn't it be better for mankind ... if as many people like these kids as possible pursued math and science more vigorously ??? Especially kids like these, who have what I would term "creative" intelligence.
Why would we want those people in law ??? That gives us far less than having them in math and science. And we will get the MOST by having them in art AND math and science. Then we'd really get their creativity going as they look for solutions to problems.
That's not to say funding such things is necessarily a waste, just the focus on STEM education may be excessive. Russia for example ended up with a lot of highly educated security guards.
Another cool application is the superconductors in the NMR devices. They can see what is inside your head and even do something equivalent to a chemical analysis (with NRM spectroscopy) without opening it. The first superconductors experiments used Helium at 4K, so they were only a laboratory curiosity.
For everyday use, I like the giant magnetoresistance. This is my favorite case to explain that strange quantum effects have real world direct applications. Just start talking about the spin in electrons. Then explain that some magnetic conductors have a different value of the current with spin up and the currents with spin down. Then add the sandwich with non-magnetic conductors. At this moment it looks like a weird laboratory experiment. Then suddenly explain how it is used in hard disks heads: http://en.wikipedia.org/wiki/Giant_magnetoresistance
Don't get me wrong, QM for example was ridiculously useful. But, pointing to past and saying these tiny particle accelerators where useful let's make a multi billion dollar one feels like cargo cult science for the lack of a better phrase. We just keep piling higher and deeper without a clear reason to do so other than we can afford to do so.
String theory is another example where lot's of effort from seemingly smart people with no practical basis.
Dumping all of LHC's money into say a large ITER style fusion project would have also been cutting edge, but there would have at least had the possibility of useful results. Hell, even ISS would qualify as vaguely useful.
How about a self sustaining bio-dome in Antarctica. Now that's probably harder and possibly more expensive, but would have real useful applications if we ever want to try and colonize Mars.
PS: Not that the 13+Billion for the LHC was all that expensive, but there are a lot of similar projects out there.
Consider, we know the first five digits of the gravitational constant. So, while it might seem like the diminishing returns are a long way off. Yet, each extra digit becomes exponentially more expensive and less useful. So, actually learning g out just 9 digits is probably a huge waste of resources.
Or in the words of a physicist, in 1920 second rate physicists where doing first rate research. Now, first rate physicistare doing second rate research.
In number theory, what's considered 'elementary' now was cutting edge in the times of Diophantus, all the way to Fermat, to Euler, to Gauss (etc). The fact that children are now routinely conversant in it, I think, is another point in favor of the importance of making such discoveries in the first place.
My point is that applications that were never envisioned for these (at the time) centuries-old-facts, are now commonplace and indispensable.
I think that there is a bit of survivorship bias that warps our understanding of old science. We remember only the great discoveries because those are the most likely to be republished and read.
Also, in the case of math, it is my impression that an amazing amount of very significant progress is being made in the present era.
As to survivorship bias, that's huge but it's not just based on good ideas. Copernicus was ~4,500 years late to proposing the sun was the center of the solar system. But, the pop story looks better when Darwin is breaking new ground instead of simply collecting more evidence in support of an old theory.
As to Amazing progress, I would hope the ~1,000,000 active mathematicians are not all wasting their time. But again, the point is we don't need to maximizing the number of Mathematicians, we are well into diminishing returns.
Has their education system declined or something else perhaps? I know they have a low birthrate....
Getting really annoyed is silly. I try not to be easily offended by hackernews comments.
In contrast, all of the science and engineering disciplines can make use of very interesting math. Not deep compared to research math, but used in a much more interesting way than in finance. E.g when you study the statistics of markets, you are just playing a game, and don't care that much about external reality per se. On the other hand if you study the statistics of DNA or gene expression, you are doing real science.
I think the best advice to a young person studying math is what was given to me at the age when I was doing the IMO (and interestingly, after I graduated by someone else): Don't neglect statistics.
Duda & Hart's "Pattern Classification" is one of the best introductions to machine learning IMO. It assumes very little in the way prerequisites, which is nice for first time exposure.
Hastie & Tibshirani's "Elements of Statistical Learning" can be a little intimidating without having been exposed to the ideas of the previous two texts. Afterwards, however, it is a gem.
It's been offered during the spring term for the past two years, so maybe Feb 2016 will see the next run.
https://www.edx.org/course/introduction-probability-science-...
In math, the model and axioms are sound (by definition) within the mathematician's world.
However, in order to make judgments about reality by using statistics, one has to come up with reasonable models and assumptions, otherwise the resulting deductions can be worthless. The leads to a lot of subjectivity and grey areas for debate that a mathematician may not be accustomed to.
However, I agree that industry and mathematics are not best friends. That's because mathematicians righteously demand and require a level of freedom and support the industry is not always willing to give because of the social problem it creates with other employees and because the value of the work of a mathematician can be too hard to judge.
From my experience, the fight to get the working conditions you need is not worth it. My advise to fellow mathematicians is that — when you want go into the industry — to go where there are already mathematicians.
At the human layer, one expression of this idea is the principle of least astonishment: "People are part of the system. The design should match the user's experience, expectations, and mental models." (Wikipedia). A system involving people is not efficient if the people are often surprised by its design, implementation, or behavior.
Efficient software solutions also tend to involve elegance. Take Git for example as an improvement over other source control systems. The conceptual primitives that Git is built upon are elegant and recognizing them as the correct basis for source control (along with a strong implementation) resulted in Git's efficiency and power.
Granted, software is different from mathematics, but I find the parallel interesting. I suspect that a mathematician's desire to find an elegant formulation, and appreciation of it, is very similar to the software engineer's.
http://andrewgelman.com/2015/03/17/1980-math-olympiad-progra...
HN Discussion: https://news.ycombinator.com/item?id=9225683
A bunch of them went into academia, though not necessarily pure math. Some became engineers and only one ended up in finance.
Some aspects of soviet education are very conducive to these competitions (e.g. an emphasis on euclidean geometry). Because of this, a top 10% student from a former Soviet country will do much better than a top 10% American if neither have extra training in this sort of competition.
If anyone is interested in discussing women in STEM in general, this article is a very poor place to do it. Eg the US has done extremely poorly up till now compared with similar English speaking country's. There are just so many idiosyncratic features at play.
I'm delighted that this is currently the top comment here. It shows we are clearly concerned with the right issues. I hope from now on all national teams participating in international competitions will be gender balanced. In order to remedy this situation we need:
1) A Twitter mob
2) An email campaign addressed Po-Shen to not repeat this and discredit his work and efforts.
3) A post of the team's picture to the popular twitter/tumblr account which shames all male conferences and gatherings
4) An email campaign addressed to IMO to implement rules that all teams should be gender balanced.
5) A solution to Poe's law.Honestly I have an extremely hard time imagining how math exams are gender biased. Have you even taken a look at this year or past imo's? You're speaking completely hypothetically and it sounds like nonsense.
Here is problem 2: Determine all triples (a,b,c) of positive integers such that each of the numbers ab-c,bc-a,ca-b is a power of 2.
As for: "perceptions of gender differentials in math" , sure that should be worked on. But it is not the fault of the contest organizes or team selectors who uses a series of objective exams and scores to determine the team members.
Edit: And as for your comment below, I'm unsure of what the particularities of Thai dress and ceremony has to to with the posited inherent sexism of maths tests. And honestly do you really think women avoid maths competitions because they might eventually meet some foreign women in traditional dress?
Q. Prove Bob has a winning strategy against Alice.
A. The Patriarchy! QED
7/7
Edit: Seriously, what could that even mean?
And logically: until that happens, the school system isn't catering for half their population.
The fact that there are statistically significantly more men among the best candidates is already enough to conclude that there was a gender bias. The bias can be in the education or in the selection process, etc.
The fact that Ukraine and Bosnia-Herzegovina have gender balanced teams mean that they have managed to avoid this bias, one way or another but not necessarily though positive discrimination, maybe they simply a more balanced education, maybe they have a more extensive selection process where they retrain the students from scratch before selection etc. Eitheir way, they deserve some credit for that.
Because in America, women are more likely to graduate high school [0], enroll in college [1], graduate from college [2], and even make up 3/5's of graduate students [2].
[0] http://www.infoplease.com/ipa/A0779196.html
[1] http://www.pewresearch.org/fact-tank/2014/03/06/womens-colle...
[2] http://www.prb.org/Publications/Articles/2011/gender-gap-in-...
As such, reasoning in terms of "ability" is fundamentally flawed because "skills" are never innate, they're the result of a lot of work and positive circumstances in a given field and starting with a handicap from the get go just makes it so much harder that it's absolutely not a level ground.
/s
In 2013, it was Finland and Costa Rica whose teams were "gender balanced", not Ukraine and Bosnia&Herzegovina. In 2012, Bolivia. In 2009, Kuwait.
Previous years stats don't suggest their education systems are anyhow different, it's just how this year's random has laid out.