Lx=d: SundayResearch

An author, Kilgore Trout, uses star system in his novels. Therefore, the same person shows up in the different stories. One of them are Billy. Billy's story is impressive for me, so I will write it here. In a certain Billy's story, Billy confronted a problem in his life. He lost the meaning of his life. He tried to re-invent it by reading science fictions. Since he tried other literatures, but they could not give him the meaning of his life. It was the last his hope.  But since his problem was in the fourth dimensional space in this world, he cannot recognize it. He asked for a help to a physiologist. One day, he saw a talk video of a famous person who recently passed away. He told people: every morning, he asked himself in the mirror, ``If today were the last day of my life, would I want to do what I am about to do today?'' and whenever the answer has been 'no' too many days in a row, he knew he needed a change.  Although Billy heard this idea before, he w...

One of the Kilgore Trout's story is called "Rational shit". Se-Cluger people are rational species, they are perfectionist and always act after think, although they don't have a time travel technology.  Each of them usually think about their comfortable houses and happiness. Everything is resolved by discussion, most of them are logical, therefore, there usually no objection to the conclusions. If the problem is not solved, some people just left to the other planets. Killing each other is not a rational solution for them. They can agree that point, that shows they are intelligent. They looked for the perfect rationality, they finally have a technology to change themselves. One day, they have perfect rationality. Energy of the planet is never wasted, all the disease were solved. The future is planned, they care their descendant. However,  they found out they will extinct one day because they are still a life form. The extinction day is far future, however, all the ...

Mutually exclusive events and independent events are not the same, therefore don't mixed up [1].  Recently, I started to read a book about probability. In the second chapter of the book [2], I have already found my big misunderstood. I didn't know this for a long time. I am not good at probability. Maybe because I missed very fundamental things like this. I thought mutually exclusive and independent are the same thing. Here, I would like to explain they are completely different concepts. Mutually exclusive events are never happens at once. An example of mutually exclusive events are head of first toss of a coin tail of first toss of a coin One coin toss, head and tail at once never happened. But independent events can happens at once. The definition of independent events is This may not be 0. An example of independent events are head of first toss of a coin head of second toss of a coin These two events are independent. But, I also find this defin...

The blog is about sample variance and Bessel's correction. What is sample variance? Why is that? Who cares? Are there any better way to choose beers? What is the answer to life, the universe, and everything? Introduction to Sample variance and Bessel's correction and Detailed explanation of sample variance and Bessel's correction

(Or how to see the 10,000 dimensional space.) Usually every mathematical area has the most important theorem, Fundamental theorem. In linear algebra, it is called Fundamental theorem of linear algebra. This is about the relationships between four subspaces: Column space, row space, null space, and left null space. But, I don't recall I heard them in my mathematics course in my university. Did I miss that? If I miss that, that is one of the most significant misses. Because I did not know the column space, I had so hard time to figure out high dimensional spaces. I know the row space (though I did not know it has a name), but this doesn't give me a high dimensional space image. I even can not imagine four dimensional space without the column space. But now, I know the column space and it is easy to imagine what is a 10,000 dimensional space. If you are interested in, please see my slides. Or you have more time, read the Gilbert Strang's Introduction to Linear Algebra. Colu...

Here is my question. The area of parallelogram is the difference of these two rectangles (red rectangle - blue rectangle). This is not intuitive for me. If you also think it is not so intuitive, you might interested in my slides. I try to explain this for hight school students. Slides:  A bit intuitive (for me) explanation of area of parallelogram  (to my site, external link) . 

Unrealistischer Träumer (4/4) Murakami Haruki Rede zur Verleihung des International Catalunya Prize am 11. Juni 2011 Wie ich bereits erwähnte, leben wir in einer vergänglichen, sich ständig verändernden "mujo" Welt. Gegen die Natur sind wir machtlos. Die Anerkennung solcher Vergänglichkeit ist eine der Grundlagen japanischer Kultur. Gleichzeitig müssen wir, selbst wenn wir in einer solch zerbrechlichen und gefährlichen Welt leben, fest entschlossen sein, munter zu leben. Wir sollten von diesem positiven Geist erfüllt sein. Ich bin zutiefst stolz, dass das katalanische Volk meine Arbeit schätzt und mich mit diesem Preis ehrt. Wir leben weit voneinander entfernt und sprechen unterschiedliche Sprachen. Selbst die Grundsätze unserer Kulturen sind verschieden. Aber wir haben doch ähnliche Probleme und ähnliche Gründe für Freude und Trauer -- wir sind alle Weltbürger. Deshalb werden so viele Geschichten japanischer Schriftsteller auf Katalan übersetzt. Ich bin sehr...