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Diary, May 2009

Sun Mon Tue Wed Thu Fri Sat
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Monday, May 4, 2009

The Hunt for Gollum

This evening, I watched the fan film The Hunt for Gollum based on Lord of the Rings, and also a documentary about how it was made. Impressive.

Tuesday, May 6, 2009

Swine flu is pandemic

Today, I read an article about two cases of H1N1 virus in Las Vegas. In itself this is not special, except that sub title reads: "Neither patient had traveled or knew anyone who had flu." Further on it says: "We've been testing people looking for additional family members or close contacts that are infected but haven't found it." This means that these two people picked it up on 'the street'. And that can only mean that the flu is already circulating without being noticed, probably through 'mild' cases where people don't even realize that they have the flu. If it is the case like this in Las Vegas, it must be the case in many other places in the world.


This evening, I biked to the university to play Go. When I arrived there were some people playing music in the bar. I found Rudi and Taco just having started a game and I decided to watch it. There were not many people watching the people making music. It also seemed like they took a long time to play which song next, and once a while some new people would jump on the stage. Around eleven, it suddenly became much busier and some new "band" entered the stage. Rudi and Taco where playing their last Ko, where the Ko threats of Rudi where related to a rather complicated life-and-death problem in a corner. When we left, I found a paper stating that from 20:30 to 23:00 was free jamming, and 23:00 to 23:30 was a performance of the The High Daggers. We left about half way the performance.

Saturday, May 9, 2009

Star Trek

This afternoon, I went to see the movie Star Trek. I had already bought my ticket yesterday, but that was a little optimisic because there were only nine people (including myself) in the room. But maybe this has to do with the fact that 12:40 is not the usuall time that people of my age go to watch such a movie. I found it a great movie, the best Star Trek movie that I have watched, and that is not because of the special effects. The movie made me laugh several times, not because of jokes, but of the strong lines. The characters in the movie match very well with those in the original series. Really a great movie.

De Slegte

This afternoon, I spend from 15:42 to 16:39 in Bookshop De Slegte. I saw many interesting books, but finally only bought these two (at 16:38:23):

Tuesday, May 12, 2009

Exact Cover

This evening, I discovered that an idea for a simple heuristic for solving an Exact Cover problem, proofed to be rather poweful. The idea is to select that vector for which the inner product of the vector with a vector counting the number of vectors that have a one in the given column. Here is the program that implements this heuristic.

Saturday, May 16, 2009

Going into the city

Today, I went into the city, as usual. I went to photo gallery Objektief where I looked at some pictures Frank Roosendaal made in Polan about saw a psychiatry and a abattoir. Next, I paid a short visit to bookshop Kruimeltje where I looked at some science fiction books. Then I went to bookshop De Slegte. I bought at 15:23:35 three second hand books, with the common theme of philosophy. These are: On my way home, I bought some vegetables: sauerkraut, pickles, iceberg lettuce, and fresh tofu. When I arrived home at five o'clock, I fried the fresh tofu and ate most of it.

Sunday, May 17, 2009

Exact Cover

This weekend, I spend some more time investigating the fastest algorithm to solve the Exact Cover problem. To my surprise, one of the most trivial heuristics, gives the best results so far. This heuristics consist of simply selecting the first remainding vector for the first position that has a minimum number of covering vectors. (I guess that the words "first" can be replaced by "random" in the last sentense, because both are determined by the order in which the problem is stated in the input file.) The implementation can be found here.

Tuesday, May 19, 2009

Death or alive

Last night I spend some hours analyzing an interesting death-or-alive problem that came up during a game of Go that I have been playing on Its Your Turn. The problem is shown on the right. It is blacks turn. Here the SGF-file with a record of my game played so far, and my answer to this position, followed by an analysis of all possible continuations by white, and how to respond to these. I hope that I did not miss anything. It was an interesting exercise.

Wednesday, May 20, 2009

Beat the Computer No. 24

In the summer of 1978, probably on Saturday, July 29, 2009, I bought a "Beat the Computer No.24" puzzle game from Harrods. I have never been able to solve this puzzle by myself. Some weeks ago, I showed it to Annabel and for one hour, as part of a bet, she tried to find a solution, but she failed. I again played with it for some time. Yesterday evening, I started writing a program to transform the puzzle into a Exact Cover. This program produced 15128 vectors with 192 positions. I used the UNIX sort command to remove all double vectors, which resulted in 13040 unique vectors. When I fed this into the Exact Cover program I wrote last Sunday, I was really surprised that it started to spit out solution by about seven or eight per second. I had expected that it would take some hours to find only a single solution. I had thought that I would have had to improve the "trivial" algorithm to make it find sufficient numbers of solutions, but it looks like there is no need for it yet.

Playing Go

This evening, I went to the university to play Go. After Taco and Rudi arrived, I showed them the game, I had been playing on Its Your Turn. They showed me a move that I had not considered yet, which might still spell disaster for me. I first played a game against Rudi (while he also played against Taco) with seven stones ahead. When he managed to kill a group, I resigned. Meanwhile Huub had arrived and I played a game against him where he got three stones ahead. It looked like I was going to lose the game, but at the end Huub made some accidential mistakes and when I could kill one of his groups, he resigned. At home I analysed the (Its Your Turn) game a little further and I found a good counter move to the problematic move Rudi and Taco had shown. The updated game record including some comments by Rudi and Taco.

Thursday, May 21, 2009

Pooh and the Philosophers

This morning, I finished reading the book Pooh and the Philosophers by John Tyerman Williams in which I started reading on 16 april, the same day, I bought the book from De Slegte at 15:23:35 for € 5,90. Honestly saying, I did not think that this is a very good book. I even thought about putting it down before finishing it. I feel it is very much like the style of Bluff Your Way in Philosophy, a book that supposedly should give you some basic understanding of philosophy but in reality is full of inside jokes that can only be understand by those that already have some knowledge about the subject. But what even disturbes me more about this book is the fact that the author takes the position that Pooh, a Bear of Little Brain, in reality is the greatest philosophical thinker in history. This is joke that soon gets boring. Some people find it a very funny book. In this sense this books differs from the other spin-off books (like The Tao of Pooh and Winnie-the-Pooh on Problem Solving) that show how Pooh and the other characters in the book unconsciously apply certain principles.

Wednesday, May 27, 2009

Playing Go

This evening, I went to the university to play Go. When I arrived, Rudi and Taco where already playing a game. I watched them for some time and then agreed with Rudi that he would play against me simultaneously with a seven stone handicap. Right within the first twenty moves, I lost some stones. In the end I lost with twenty points. Then I followed the game between Rudi and Taco till the end, after which we went home quite soon.

Saturday, May 30, 2009


Tonight was museum night. I decided to visit Rijksmuseum Twenthe in Enschede because I had read somewhere that the entrance was free and I wanted to see the painting by Monet. The last time I visited the museum on Sunday, August 3, 2003 together with Annabel, it was not on display. When I arrived, I discovered that the museum was only free for people with a button from the Balenfestival and that that button costed 5 Euro. I decided to buy it and walked through the museum. Hereby a list of paintings that I found interesting: Afterward, I biked to Twentse Welle and walk around a little. I also watched a young man blow glass (picture).

This months interesting links


KMZ file of movements.

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