2014-11-28

The meaning of ``Get together'': Part 3

I like to make a quiz like in the last article. But some of my friends said to me ``Many can live without knowing such things.'' That would be true. I even thought that it is natural that many people don't care about that. But recently I found some people deceive others by using this kind of wrong math. I feel sad when the honest people were deceived. Especially when I read a newspaper article that someone used this kind of wrong logic and stole some money from people. I think it may be good to know these kind of things not to be deceived by malicious people.

The problem here is actually not exactly a mathematical problem, it is rather a language problem. If you understand the meaning of the problem, actually this is not so much math in there.

Since the question is described in a language (originally in Japanese, here in English. I found it is interesting this worked for both languages), we need to understand what the problem means. Here we need to know what is the 'goal success ratio' and what does 'get together' means. I wanted to him to think about these words really means. A goal success ratio is actually simple. It is the ratio of how many shoots were tried and how many goals were succeeded. But I didn't realized for a long time, I found people actually don't think about what is 'get together' means. When I found this, I made this problem. Here I made up an expression that adds two numbers together, but the result doesn't change. This is a strange calculation, isn't it? I use the double meanings of the 'get together' to make this happen.

I coincidentally find that the words 'get together' is actually not a simple expression. Language is a deep subject. The phrase is used so often, we are just too familiar with that. But sometimes I can find something so familiar, thus I thought I knew it well, but I actually didn't know about it. Maybe similar things happens with a person. I think I know someone well, but one day I realized I didn't know that person well... This is a blind spot. If you learn literature, you may deeply think of each word you are using. However it is hard to do in the everyday life. But if you don't realized what is wrong here, that means you may think that adding non-zero numbers don't change the amount. Someone could use this method as a fee calculation or a tax calculation. It seems you didn't pay much at the amount, but you actually pay a lot. I don't want to people are deceived by this kind of wrong logic. Since I am living in a democratic country, if many people are deceived, I will also deceived. Actually I am forced to be deceived. That's democracy.

This boy understood the meaning of the question. And he found my lie. Then, he asked me, ``Does a teacher lie?'' This was an excellent question. I answered, ``Of course! A teacher would lie. But, most of the cases, a teacher actually doesn't lie, but a teacher may make a mistake. If you could find that by thinking yourself, I am really glad.'' (I also hope he has a good communication skill since I had a lot of trouble of lacking the skill.)

Any authority, like a teacher, might lie and might make a mistake. Many of my generation knows words: ``We, adults, don't lie on purpose, but we make mistakes.'' when a famous cartoonist in Japan made a fatal mistake in his story. The boy realized it. I wish he continues to try to understand the world himself, not just following the authority. I just teach him one method to think himself through mathematics. We could also think through learning literature, or foreign languages, and so on. But I think it is a good start. I am so glad he found this by himself.

Nowadays, our life is deeply based on science. Thus I believe there is a basic science knowledge we, all the citizen, should know about it. In many countries, everyone needs to learn some science in the elementally school. I think this is not for making everyone scientists. We need to know the infrastructure of our society. For instance, we cannot completely ignore where the electricity comes from. It may affect the environment, and I recall the Fukushima incident. We should know some concept of computer security, otherwise we cannot safely buy anything through the internet. I believe we all need some basic knowledge about math and science in our society. I will be happy if my article is one of the clues for someone who later become curious to science or mathematics.

In this article, I didn't exactly explain what is the problem in the question. But 13 year-old boy can find it. I also put some hints in the article, so I hope you think through the problem. Please don't search it immediately. Let's think first before searching the answer on the internet.

2014-11-26

The meaning of ``Get together'': Part 2

A while ago, I taught mathematics to a thirteen years old boy. His family moved to another city, so we could not have more sessions, but I liked to teach him.

In the last session, we discussed about addition of fractions. If we get a half cake (\(\frac{1}{2}\)) and a half cake (\(\frac{1}{2}\)) together,
\begin{eqnarray*}
 \frac{1}{2} + \frac{1}{2} = \frac{1+1}{2} = \frac{2}{2} = 1,
\end{eqnarray*}
it becomes 1. If we add fractions with like denominators, we only add numerators. We discussed why we did in this way and what this meant.

Then I told him a story. The boy's favorite soccer player tried to shoot the goal twice in a game, and he succeeded once. His goal ratio of this game is \(\frac{1}{2}\). (Two shoots, one goal) The next game, again he tried to shoot the goal twice in the game, and again he succeeded once. His goal ratio of the game is again \(\frac{1}{2}\). Let's think about his goal ratio to get two games together. For these two games, he tried four goals in total, but succeeded twice in total. Therefore, his total goal ratio is:
\begin{eqnarray*}
 \frac{1}{2} + \frac{1}{2} = \frac{1+1}{2+2} = \frac{2}{4} = \frac{1}{2}.
\end{eqnarray*}
The goal success ratio is correct. However, how is \(\frac{1}{2}\) + \(\frac{1}{2}\) equal to \(\frac{1}{2}\). That must be 1. This also violated the rule of fraction addition. If we got two \(\frac{1}{2}\) cakes together,
\begin{eqnarray*}
 \frac{1}{2} + \frac{1}{2} = 1,
\end{eqnarray*}
but, when we got two games goal ratio together,
\begin{eqnarray*}
 \frac{1}{2} + \frac{1}{2} = \frac{1}{2}.
\end{eqnarray*}
I asked him why this happened. It is quite strange that one addition expression has two different answers. 1+1 is only equal to 2. There should not be two different answers of one addition, like 1 + 1 = 2 and 1 + 2 = 1 at the same time. Therefore, at least one should be wrong.

We discussed this problem. He first told me the total goal ratio must be 1 as the cake's addition. But I added one more game, the player tried two goals and one success, then in total three games,
\begin{eqnarray*}
 \frac{1}{2} + \frac{1}{2} + \frac{1}{2} = \frac{3}{2}.
\end{eqnarray*}
Now the goal success ratio is \(\frac{3}{2}\). This means this player tried two kicks and he got three points. How it could be possible? At that time, his father just passed by us, and made a joke, ``He is the best player, he could get three points with two shoots.'' But we all know that is not possible, so something wrong in this calculation. When we want to get all the three games together, his goal ratio should be
\begin{eqnarray*}
 \frac{1}{2} + \frac{1}{2} + \frac{1}{2} = \frac{1+1+1}{2+2+2} =
  \frac{3}{6} = \frac{1}{2}.
\end{eqnarray*}
Since he always success one goal per two shoots. In other words, he tried six shoots and succeeded three goals, this means his goal success ratio is \(\frac{3}{6}\) which is \(\frac{1}{2}\).

Our discussion continued more than 20 minutes, but at the end, he found what is the problem. Why this strange thing happens. I was impressed. It was a great moment for me and hopefully also for him.

The following article will be the conclusion of this story.

2014-11-25

The meaning of ``Get together'': Part 1

Every person thinks by words. Thus words are important for me, too. Especially I need to write programs to realize an idea through the words. We can easily find that one word has sometimes a few meanings. People make a joke from it. I think one word has a few meaning is quite natural. For instance, ``run'' has a few meaning. I run as I move fast by foot. I can run a shop. A movie is now running at the theater. In English, it has more meanings with a short word (run after, run away, run out, ...), however, you have already seen the ``run'' itself has a few meanings.

When we used only one language, we hardly noticed this multiple meaning of a word. However, when we learn foreign languages, we need to notice this through the translation. We can easily see one word usually has more than one translation in a dictionary. When we learn a foreign language, we can usually see the deepness of both our own language and the foreign language. In literature, especially in poems, using the double meaning of word is important. In the book 1984, Orwell describes Newspeak to restrict the people's ideas by eliminating the double meaning of the words. If you learn a modern computer language, you'll find some of the languages have a concept ``overloading.'' One name can have a few implementations. This is an adaptation to the human being uses the same word, but different meanings. If you learn mathematics, you can also notice some operators have different meaning depends on the context.

I sometimes feel the literature and mathematics share a common concept. Some people (e.g., Lewis Carroll, Noam Chomsky, ...) are good at both literature and mathematics. I would imagine they might also feel this common concept.

I sometimes feel that thinking about what I am really saying, is important since one word can have a few different meanings. I recently have an experience about this, so I will write it in the next blog article.

2014-11-11

Frontline Volunteer

My closest person offered him a volunteer to fight Ebola. He is just a programmer and neither a doctor nor a nurse, so I wonder what he can do for that. However, the frontline people need not only doctors and nurses, but also support people. He found a position of IT, the frontline people will establish a data center for outbreak and information hub.

I asked him, ``Don't you have a fear to do that?'' He answered me, ``I'm scared.'' The Ebola has a high risk of death, 50 to 90% of death ratio once infected. There is no good medicine for it yet.

But he thought, the outbreak must be stopped there and must be stopped still we can. He told me he doesn't have any family, so he just felt that he does it better than someone who has a family does. Although he clearly sees what he should do, still his hand was trembled when he pushed the ``send'' button of the application form.

For one week just after he sent the form, he continue to think about what he should do before he go. His hobby is making introductory math videos for children. He just continued to make them. He told me it was a quite productive one week. But I know the work is never done in a week, so I wonder it is good thing to do or not. He seems to feel what I am thinking, he told me that, ``I could not find any other things I need to do now.'' He also tried to find some medical training that he could do in Berlin. But, it is not so simple.

One and half a week later, he got a letter: This time the frontline allies are not expressing an interest in volunteers with his skills, profile, and availability. But the frontline situation is always changing, if the frontline needs him, they will let him know right away. I think his specialty is only for computer and maybe the frontline people need the people who know more about medical stuffs. He didn't talk about this anyone until he got this letter.

He told me that that one and half week was a special week for him. He had a strange feeling. He thought ``If I could not come back here again....'', but he also thought ``What do I want to do even I could come back?... I have nothing special.'' Then he realized that it makes much sense he helps to stop the disease.

But, he made one plan, he thought it might be the last plan. His friend's child will have a birthday at 18th of November. He bought a ticket to Dresden and he wanted to celebrate her birthday before he leaves.

Gap time volunteer: Lunch break volunteer version

I call a fraction time ``Gap time''. A gap time is for instance, a time I am waiting for my next train, a time I am waiting for someone at a cafe, my commute time, and so on. Everyday I have some fraction time that I need to wait something a bit. I have a volunteer work for translating education materials. I often use this ``gap time'' for it.

I'm a lazy person, therefore I could hardly find some amount of continuous time for my volunteer work. I believe if I work hard, I cannot continue it. Thus my strategy is ``don't work hard, do just small amount only, but continue everyday for long time.''

I translate Khan Academy learning materials and its site to Japanese and German. I could translate English to Japanese alone, but I need some help for German translation. I ask to help for this at the lunch break gap time. When I and my colleagues go to lunch, I ask someone to proofread my translation while we are waiting for our coffee. This is a lunch break volunteer.

I translate one or two math exercise problems almost every day. I printed it out and bring it to our lunch. We often go to our favorite coffee house after the lunch, I ask one of my colleagues to proofread my translation at there. One of six colleagues help me out at once. Here is a snapshot picture of how it looks like. The pictures below are an example of proofreading and some of them.

Lunch break volunteer snapshot
A sample proofreading result
Recent results
We do this for one and half year. The amount of translated words is around 410,000 words (Japanese) and 40,000 words (German). For German, we only did it in weekday, five to ten minutes per day. We continue this for one and half years, and I see a great progress. Since this is around 1% or total necessary work, we only need 100 people to do this. I am the slowest translator among German Khan academy translators, so practically we don't need 100 people. There are some active volunteers for German translation, so they have good progress. On the other hand, currently only two volunteers (including me) are working Japanese translation, so it will take a while. I limit my time to maximal 25 minutes per day for German translation. I don't want to push my colleagues, so I also limit the length of the translation per day. The next figure shows the progress of recent one year.

Crowdin progress graph from 2013-11 to 2014-10

How do you think this way to join a volunteer activity? I recommend this method. I only use the time at our lunch coffee break for this volunteer. Sometimes there is no volunteer since we go to ice creame house instead of the coffee house. A gap time volunteer is not so hard to do, but if you continued it, the result is impressive. How do you think to try something out in this way?

Acknowledgments

Thanks for my proofreading helpers: J.M., J.R., C.W., D.S., N.B., D.S.

2014-09-29

A solution of a kernel panic Debian 7.6 + NVidia GTX 770 at the boot time.

One of my friend had a problem with Debian 7.6 + NVidia GTX 770. When he booted the machine with the graphics card, the kernel panics at very early stage of the boot.

The reason is that the nouveau driver seems not supported this GPU.

So the solution is black listing the nouveau driver. If you install the NVIDIA driver, /etc/modprobe.d/nvidia-blacklists-nouveau.conf does the job. Therefore, before installing the card (hardware), installing the NVIDIA driver is a solution.

2014-07-13

The day Japan doesn't keep their own constitution.

2014, July 1 will be remembered as the darkest day in the history of Japan's constitutionalism because of the Abe Cabinet's approval to change the government interpretation of the supreme law to allow for the exercise of the right to collective self-defense. (cited from Asahi Shinbun, http://www.asahi.com/english/articles/AJ201407020044.html)

2014-06-15

Next machine translator


Thanks to Daniel, Jörg, Pascal, and Shinosuke.

The followings are copy-and-paste-able text. (Added 2014-6016)
  • US English: Please jump from here. Then you will be a hero!
  • UK English: For Queen and Country, please jump here!
  • French: Sautez, de charmantes demoiselles vous attendent en bas!
  • German: Achtung! Jetzt springen! Stehenbleiben verboten!
  • Japanese: ここから飛び降りましょう.皆さんそうしてらっしゃいます!
  • (On the notice board: B!Tufsfpuzqf!usbotmbups/!Ubuflbxb!Tijoptvlf!upme!bcpvu!tufsfpuzqft/Uibu!xbt!pomz!qfpqmf(t!tufsfpuzqf/!Cvu!J!xpoefs!jg!b!usbotmbujpo!qsphsbn!dbo!vtf!uif!tufsfpuzqf/)

2014-03-30

Oracle Virtualbox 4.3.10 mount shared folder issue

I have an issue of mounting Windows 7 (host) folder from Ubuntu12.4, 13.10 (guest) of Oracle Virtualbox 4.3.10. So I reverted to 4.3.8. Though, it seems there is a workaround.

  https://forums.virtualbox.org/viewtopic.php?f=3&p=283645#p283637

2014-03-09

Mad world dance in Berlin

I saw a dance in front of the Brandenburger Tor yesterday.

I was surprised that a dance has such expression ability. So many things I don't know yet.

Mad world dance in Berlin (2014.3.8)
In the main part of the dance, without so much explanations, I can see (or it may just my misunderstandings) the Olympic athletes swim to the Fukushima daiichi led by the prime minister Shinzo Abe who declared "the "The radioactively contaminated water has been completely blocked." Then, Abe did nothing, but to demonstrate the fish safety, he ate the fish near the power plant. and so on.

My favorite part of this dance is the ending comment. Many can do satire and say, "oh bad... What's going on", I think it is important to show what is the problem, though, it's a bit depressing. 

But the dancer's last comment was "Let's make a different future because it is possible if we all do something." I think this is a great message for the hope. 

I like this dance and recommend to see, here you can find the movie. http://vimeo.com/88526070

By the way, the government decision announce page related leakage has been removed  http://japan.kantei.go.jp/96_abe/decisions/2013/osensui_e.html. You can see the page in the Google cache with search keyword "Fukushima daiichi contaminated water" and follow the link. This may be some page reorganization, but it's a bit inconvenient.) and again, 100 ton's 2.3*10^9 Bq/l  water leakage. (http://www.asahi.com/articles/ASG2N35BPG2NULBJ005.html) 2014.2.20.

2014-01-17

An energy company uses exponential power.


Question 

In Rabbit city, Mr Fox generates electricity energy. One day, Mr Fox realized there is no one else generates the energy. So he decided  raise the price every year for 30 years since that year he retire. He met his uncle, who is working for the city hall. Mr Fox said his uncle, ``I would like to raise the price 10 Euro for currently 100 Euro paying rabbit.'' His uncle answered, ``It seems you don't know about economy. You should say, I will raise 10 % every year.'' Which statement of following is correct? Mark all apply.
  1. It's same raise when you start 100 Euro and 10 Euro every year and when you start 100 Euro and 10% raise every year. Since 10% of 100 Euro is 10 Euro. Therefore, 30 years later, how much raise the price is 10 * 30 = 300, and plus original price 100 = 400. It becomes 400 Euro after 30 years.
  2. Mr. Fox's uncle is correct. 30 years later, 10% every year raise is twice as much as 10 Euro each year's raise. The raised cost is around 600 Euro and the cost becomes 700 Euro.
  3. Mr. Fox's uncle is correct. 30 years later, 10% every year raise is five times more than 10 Euro each year raise.

Answer

10% every year is much higher raise than 10 Euro each year raise.

  1. First year raise: 100 * 0.1 = 10, + principle price 100 Euro = 110 Euro.
  2. Second year raise: The price is now 110, so 110 * 0.1 = 11, + current price 110 Euro = 121 Euro.
  3. Third year raise: The price is now 121, so 121 * 0.1 = 12.1, + current price 121 Euro = 133.1 Euro.
  4. n-th year price can be calculated by $100*(1.1)^n$. 30 years later, the price is $100*(1.1)^{30}$ = 1744.9 Euro.

Do you understand why Mr Fox's uncle suggested 10% raise instead of 10 Euro every year?  Some people use this trick as ``Every year, the same raise, 10%.''  It sounds like every year the same absolute price raise, but, actually every year you pay more and more. If you learn math, please don't be cheated.