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Diary, February 2009

Sun Mon Tue Wed Thu Fri Sat
  1   2   3   4   5   6   7
  8   9  10  11  12  13  14
 15  16  17  18  19  20  21
 22  23  24  25  26  27  28

Sunday, February 1, 2009


This morning, there was a thin layer of snow on the ground, so thin that it did not cover everything. I did not notice it immediately. During the day the temperature remained below zero degrees Celsius and there was a moderate wind from the East.

Tuesday, February 3, 2009

Richard Guy

This morning, I received an email from Richard Guy about some of the interger sequences that I contributed to On-Line Encyclopedia of Integer Sequences. He was interested in the recurrence equations for the sequences A003696, A003733, and A139400. I answered him that the first two can be found on the page "Results of counting specific spanning subgraphs of the graphs G x P_n" (which is part of the page "Counting Hamilton cycles in product graphs"), namely here and here. The third sequence, that was entered by Paul Raff, does give a recurrence equation but not all of the initial 32 terms that are needed to define all terms. I compiled the counting program and calculated the first 100 terms and also included the matrix in the output. The recurrence equation is related to the eigen-polynomial of the matrix. He also asked if the paper "On the number of specific spanning subgraphs of the graphs G x Pn" was published and if he could get a preprint. I send him the link to an earlier version of the paper.

I also asked him, if he could send a link to his home page. Only in the afternoon, I discovered that Richard Guy is quite a famous mathematician. I am happy that I could make a contribution to his research into divisibility sequences.

Wednesday, February 4, 2009

Neil Sloan

Yesterday evening, I got an email from Neil Sloan, who is the maintainer of the On-Line Encyclopedia of Integer Sequences (OEIS). Through an email from Richard Guy he became aware of the page Results of counting specific spanning subgraphs of the graphs G x P_n. I already had submitted many sequences from that page to the OEIS. He was unaware that many of the sequences where published in a paper. The rest of the evening I spend writing a detailed answer to his enquiries. This morning, I got a reply from him. He has added the missing sequences to the OEIS and also included the recurrence equations. Some of which are now among the largest in the database. He also send me a list of corrections to my pages. I promised him to over these and also check all the sequences that added.

I think that the OEIS is a great means for bringing mathematicians together, because for many mathematical problems it is possible to derive a interger sequence and by searching for the sequence in the OEIS it is possible to find others working on the same problem, or even discover interesting relationships between mathematical problems that are widely apart.

Playing Go

This evening, I had some trouble entering the campus of the university. There was a soccer-match going on between FC Twente and NAC Breda and some police agent waved me to the right just before I wanted to go under the bridge which leads to the round-about at the entrance of the campus. I almost hit a person on a bike when I turned to the left, but I could brake just in time. In fact, I was already unconsiously braking, when I turned. A little further I made a U-turn and through another road, I arrived at the round-about and could enter the campus without problem. I still don't understand why I could not go under the bridge. When I arrived, Rudi and Huub were already playing a game of Go. I watched their game, and when they finished, Rudi suggested I should play against him. We agreed on a four stone handicap for me. But already soon, I felt lost, and not being able to win the game, and by playing some silly moves, I only made things worse. At one point, Rudi encouraged me to continue when I thought about resigning. But when I for the second time, lost some stones, I resigned. If I would not have lost those stones, I still would have lost. Rudi and Huub analyzed the game, while I just watched them. In a certain sense Huub is really stronger than I. I am not even going to bother about trying to reconstruct the game record this time.

Sunday, February 8, 2009


This afternoon, I spend some time to fill the new bookcase besides my bed. I placed the second bookcase last Saturday, besides the first. I am already thinking about placing a third bookcase beside my bed. After I finished placing the books, I took a picture. The two top shelves are filled with my diaries from right to left. The second shelve of the right bookcase has my most beloved novels. The fourth shelve is filled with books that I still have to read. The second shelve of the left bookcase has more novels and books I like. The third shelve has bibles and christian literature. The fourth shelve has games and DVD's.

Monday, February 9, 2009

Some light snow

This morning, there was some snow on the grass in our back garden. When I left to my office, it started to snow, and it kept on snowing for about an hour. The snow stayed on about half of the surface area of the ground. Through the day, the snow disappeared.

Tuesday, February 10, 2009

Wet wet snow

This afternoon, we had some wet wet snow falling from the ski. It was already wet, when it was falling down, and would leave no trace on the ground.

Wilders refused entry to UK

Today, came the news that Geert Wilders has been refused entry to the United Kingdom. He wanted to London on Thursday, but today he received a letter telling that he was not welcome, because his visit constitute a threat to public order. He still want to go. Dutch Ministers are quite upset about this. Ernst Hirsch Ballin, the Minister of Justice, told his British colleague Jacqui Smith that people of the parlement should be free to express their thoughts. However, it is also this Minister who suggested that the constitution should be changed such that insulting a certain faith would be equivalent with insulting its believers. (He is also the one who caused Gregorius Nekschot to be arrested.) It is this same idea that is found in the court decision to order the prosecution of Geert Wilders. And it is this prosecution that probably played a role in the decision of the government of the United Kingdom to refuse Wilders, or at least a way to justify it. It seems that freedom of speech is rapidly disappearing in Europe.

Wednesday, February 11, 2009

Wet snow

When I left for home this afternoon, I noticed that it was snowing. At first I thought it was just the kind of wet snow we also had yesterday, but the closer I came to home, the more white patches I saw on the ground (mainly on the grass). So the snow was not as wet as it seemed. Still I would classify it as wet snow.

Playing Go

This evening, I was shortly after nine that I arrived at the university to play Go. I was a little surprised to find only Rudi, who was about to leave for home soon, if I would not arrived. We agreed on a seven stone handicap for him. About half way the game, when I was already getting behind, Huub arrived, and he followed our game play. We did play a Ko during the end game, but it was kind of useless, because I lost with 40 against 52points. We analyzed the game till and when I arrived at home, I tried to remember the game and came up with a game record. Huub will send me some pictures he took, so maybe I will be able to extend the record a little further.

Friday, February 13, 2009

Geert Wilders

I am a little surprised that in the British press Geert Wilders is described by terms like "far right", "someone in the margin of extreme right", and "populist twit and bigot" and said to encourage extremism. I wonder whether these people realize that about 15% of the Dutch are supporting his party (PVV) at the moment (according to a recognized popularity poll) which is barely less than the Dutch Labour party (PvdA) would get. It also makes it the third largest party of the nine parties that where elected into the parlement. Support for Wilders grew substantial after a court ruled that he should be prosecuted. Furthermore, it should be noted that much larger part of the population worries about the slow but steady islamizations of the society and the restrictions on the freedom of speech that seem to be caused (directly or indirectly) by the muslim minority. This is supported by the fact that 50% against 46% of the population feels that Wilders should not be prosecuted.

Wet snow

The whole day there was wet snow falling from the sky sometimes mixed with some rain. Around four o'clock the sun started to shine, but a quarter of an hour later it was dark outside and it looked like there was some fog, but it was just snow.

Saturday, February 14, 2009

Going into the city

Around one o'clock Li-Xia and I went into the city. She gave me a little scare, when she turned left just before an approaching car. After we parked our bike, I bought a currant bun from Bakkerij 't Stoepje. Next I bough some Soggus rye bread from Bakkerij Verbeek. We talked a little at Gallerie Beeld en Aambeeld. I heard that the paintings by Billy Foley are still at the Faculty Club at the university. At the De Slegte bookshop I first bought the following three books for 10 Euro: We walked around a little more and at 15:07, I bought the book Lover of loser, your choice for € 8.50 by Carry Slee as a present for Annabel. Next we went to bookshop Broekhuis, where went to get a free CD for a ticket which I got when I bought the book Maak jezelf maar klaar by Elsbeth Etty on January 5, 2009. Because I could not make a decision, Li-Xia selected a CD with Symphony No. 9 by Beethoven. We walked back to market, where I bough another currant bun and 490 gram of bean sprouts. Then we went int the department store V&D where I bought a tiny dictionary with the title Drop je lyrics 2 about teenage slang for two euro. On the way home, I bought some fresh tofu. We did some groceries and arrived home around four o'clock.

Sunday, February 15, 2009


When we left church, about half past twelve, there was some snow falling from the sky and the sun was shining through some thin clouds. I immediately made some remark about a snowbow in the sky, although I knew that such a thing does not exist. It kept on snowing on and off during the afternoon, but it was only at the end of the afternoon that some of the snow stayed on the ground.

Tuesday, February 17, 2009


According to this article, men really do see women as 'objects'. Professor Susan Fiske reports the discovery that when men look to half naked women a part of their brain becomes active that usually reacts to objects and that some other part, that is involved in social interactions gets deactivated. This effect seems to be stronger in men with sexist tendencies. But can one really draw any conclusion about whether men truely, literally see women as objects in these circumstances? Susan Fiske states: "They are not treating them as fully three dimensional humans." But it would not surprise me if the part of the brain that is active when viewing objects, is very much involved with seeing three dimensional. I have noticed for a long time that I can somehow switch between two dimensional viewing and three dimensional viewing. Three dimensional viewing takes much more energy and is involved into construction a three dimensional volumen representation of an object (or human body for that matter). It already has been known for a long time that men do take measurements of female bodies as part of their evaluation of a womens attractiveness. Furthermore, she suggest that seeing a lot of "sexualised images of young women" causes men to see women more as objects. I am getting the wierd feeling that this line of thought is rather sexist and cannot be confirmed by her finding. She could only make that conclusion when she would have compared men from different types of societies. I really doubt if a significant difference would be found.

Wednesday, February 18, 2009

Playing Go

This evening, I went to the university to play Go. I was the first one to arrive. Not much later Huub arived. Rudi had told us last week that he probably would not make it. We decided on a game where he would get two stones ahead. Somewhere in the middle, I played a little to hasty in the excitement of the game, and allowed him to connect a group of stones that otherwise might have been dead. Go is not only a game of thinking, but also of being able to control oneself. In the end game, I also made a pretty big mistake, and lost a whole group of stones. At that point I resigned, but we continued playing. I lost with 43 again 15, I am not mistaken. We replayed only a small part of the game.

Thursday, February 19, 2009

More (wet) snow

This morning, when I looked at the Dutch rainfall radar, it indicated that there was precipitation in our area. When I looked outside, I did not see any signs of rain. This sometimes happens that the rainfall radar gives a false positive. But when went outside, I noticed some small white snow flakes falling from the sky. It even got a little stronger when I biked to my office. But non of the snow stayed on the ground. In the afternoon we got some more snow, which at someplaces did stay on the ground. It surprise me that we just keep on getting this kind of wet snow.

Friday, February 20, 2009


Yesterday evening, I spend some time constructing a KML file with Google Earth about a F3 tornado that occured in the Netherlands on June 25, 1967 based on information I found on a web page of the Royal Netherlands Meteorological Institute. I heard about this tornado through the book Maak jezelf maar klaar by Elsbeth Etty which I am reading at the moment. The book contains a fictional diary written in the year 1967 and for this reason it frequently makes references to historical events that took place in that year.

Tuesday, February 24, 2009

Alzheimer's related to liver?

According to the press release New Study Provides Insight Into Ways Organ Systems Outside the Brain May Affect Alzheimer's Disease (related to the scientic article Peripheral Amyloid-b Levels Regulate Amyloid-b Clearance from the Central Nervous System) there seems to be a connection between the functioning of the liver and Alzheimer's disease. I find this information quite interessing and worthy to investigate further.

Wednesday, February 25, 2009

The Powned betting game

In the Netherlands anybody who can collect enough members can start a subsidized public broadcasting company. The people from the popular blog Geenstijl (styleless), who contributed to the resignation of Ella Volgelaar, Integration and Housing Minister last year, are now planning the start op Powned. They have to get 50,000 paying members by April 1, 2009. At the moment they have 33,407 members and with the current progress it is not very likely they will make the required number of members. To become a member you have to donate € 5,72 (which, before the Euro was introduced, was equal to 10 Dutch guilders). They promised to return the donation plus 25 cents (€ 5,98) in case they will not make it. This makes, what I would call, the "Powned betting game". The question is, what is the right moment to become a member to make a profit out of it.

Creation or evolution?

Because of the Darwin year some orthodox christians thought it was a good idea to distribute a bible tract among all Dutch households to explain that evolution has not been proven and that creation is a viable option. When some people heard about these plans, they started a campain to return the tracts to the sender and opened a website with the title (in Dutch) "Back to your maker". I find it strange that some people have such a problem with receiving such a tract through the mail, as they receive loads of advertizements every day. There were even some people sending death threats. I know, these should not be taken so seriously, but still I find it strange. According to a poll: 19% of the Dutch do not believe that evolution is a valid theory. To me evolution seems to be a more valid (scientifical) theory that the idea of creation in six days about 6000 years ago. Most people do not realize that the greatest theological problem with evolution is that it contradicts with the idea of the fallen men, and thus cancels the need for a Saviour. Still, I find the idea of a God that sacrifices Himself as way to save people, a very attractive and genuine thought. Evolution does not explain subjective consciousness or reduces it to mere imagination ("I am only self-conscious when I think about it"). Evolution theory does not cancel moral law. Moral law could have arisen from evolution, because it enables cooperation among primary selfish individuals, in case when cooperation increases the reproduction rate of those who cooperate. However, evolution theory by no means is an answer to the two big questions.

Saturday, February 28, 2009


Shortly before four o'clock in the afternoon, Li-Xia and I left for the city. When we parked our bikes outside bookshop "De Slegte", we saw a sign saying that they where sellings encyclopedia's for ten Euro. On the second floor we found a Grote Spectrum Encyclopedie for ten Euro. I guess this price is even less than the price the raw paper if you would hand it in for recycling. I remember how I used to page through this encyclopedia when I was in highschool. (On I found one being given away for free.) Li-Xia encouraged me to buy it, but I felt that we did not really have a place to put it. I did buy some other books. Three books in the 3 for € 10 category and one book about a woman with a 52 year old husband being diagnosed with Alzheimer's Disease. The books are: While we were in the shop, my phone rang. It was Annabel, who told me that she would join us for dinner at Camel. At home, I started to read A year with 1000 days.

This months interesting links

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