Per Definition

Kan innehålla spår av matematik

2010-03-14 Happy Pi day

Here in Indiana, we have a little different value for Pi:
http://en.wikipedia.org/wiki/Indiana_Pi_Bill

http://www.math.su.se/~per/index.php?year=10&month=03#entry-2010-03-14-22-30-14

2010-03-13 Categories and functors

Today, I realized that I have found (and used) a non-trivial invertible functor from my categories of infinite trees and the morphisms which are monodromy actions on these trees to a similar category, but with other trees and morphisms. I have used this to simplify my data structures in my Mathematica program. So I have inadvertently applied category theory to simplify my Mathematica program. This is quite surprisingly, since I consider category theory as general abstract nonsense.

I never thought that a day would come when I applied category theory to anything. I must say, trying to explain this to my adviser was really hard...

The schedule for today is to write down this, and then start enjoying SPRING BREAK!

http://www.math.su.se/~per/index.php?year=10&month=03#entry-2010-03-13-01-06-00

2010-03-07 Sushi

I was following my friend to the public library yesterday, and on our way, I found a Sushi shop! I have been craving for fish for a long time now, so I was very happy and I had lunch there today.

It is a bit embarrassing that I have lived a block from the library and that sushi shop for two months now without knowing it...

Right now, I am looking forward to Monday, as I plan to experience the benefits of being in one of the most conservative states of the US.

http://www.math.su.se/~per/index.php?year=10&month=03#entry-2010-03-07-04-19-06

2010-03-06 The talk

My brother is ten years younger than me, and he will become a teenager this year. For some people, it is probably too early, but he is quite mature and I believe it is time for "the talk".

I believe that it is much better to learn a lot of it at once, instead of bits and pieces from the internet and the school. My parents rarely talk to me about the subject, but as a role model, I consider it as my duty to at least teach him the basics about genus and discreetness. Also things like openness are so important these days, and also the fact that you always have a choice. But there is also more basic questions to be answered, like how to form a pair, and be a union.

Later on, I can explain what subspace means and give some references to where one can find a good knowledge of knots.

But I have never taught someone on this subject, especially no one of such low age, so if you have any tips on how to teach Set theory and Topology to a teenager, I will be very happy to receive them.

http://www.math.su.se/~per/index.php?year=10&month=03#entry-2010-03-06-04-31-43

2010-03-04 Problem with age

The following 365 days, you cannot express my age as a sum of eight cubes of non-negative integers. How old am I?

Hint: You may assume that I am strictly younger than 239 years.

http://www.math.su.se/~per/index.php?year=10&month=03#entry-2010-03-04-16-06-46

2010-03-01 Images from my room

Here are some images from the first week.
My room have not changed much since.

















Here is an image of a classic American snack. I don't think you are supposed to eat beef jerky with pasta, but I found it to be a satisfying combination.



Some day, I will take some pictures of the squirrels that run around campus.

http://www.math.su.se/~per/index.php?year=10&month=03#entry-2010-03-01-02-18-24

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