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Diary, February 2019

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Friday, February 1, 2019


At 17:58, I bought the book Eindexamenwerk 1983 written by Sipke Huisman in Dutch and published by Akademie voor beeldende kunst AKI in 1983 from charity shop Het Goed for € 1.50.

Saturday, February 2, 2019

Exhibitions and books

This afternoon, I went to Tetem art space to have a quiet look at Walk-in Worlds. I watched the following three Virtual Reality 360° movies: Celebrating the Holy Object: You, Passing Down Poetry, and The Big Dance. The first one was recorded in Rijksmuseum Twenthe in the exhibition Ars Longa, which I visited last year. Next, I went to bookshop Broekhuis. On the top floor, I watched the exhibition with works by Simone Zacharias. I had seen this before briefly. I was intriged by the work Paarse Dag 2 and consider to buy it. At 16:40:50, I bought the following two books:

There was a lot of snow today, but it was mostly wet snow. At the end afternoon, the snow began to stay at some places.

Monday, February 4, 2019

The Red Line

This evening, I saw the exhibition The Red Line at the Vrijhof building of the University of Twente. This exhibition shows pictures taken by the members of Amateur Photographers Association Drienerlo Foton around the theme of a red robe, which occurs in almost all pictures, and in the exhibition connects the pictures.

Tuesday, February 5, 2019


Today is the first day of the year of the pig according to the Chinese calendar. The spring festival has begun.

Hexagon numbers

This morning, I wondered what are all the areas that you can create with a (possibly irregular) convex hexagon on a triangular grid. The smallest such a haxagon consists of six triangles. By extending one side with four triangles, you get an irregular convex hexagon of ten triangles. It seems that there are some considerable gabs. I wrote a small program to find all sizes below a hunderd, and it found that the following sizes (larger than six) are not possible: 7, 8, 9, 11, 12, 15, 17, 20, 21, 23, 29, 36, 39, 41, 44, and 84. I was surprised about the lonely 84 and wondered whether there might be another much higher lonely number. Also wondered whether it would be possible to proof that above a certain number, all numbers occur as the size of such a hexagon. This evening, I realized that it is probably easy to proof this. A triangle grid is equivalent with a square gird with one diagonal added. Then every hexagon fits in a rectangle where two opposite corners have a triangle removed. The number of triangles in the rectangle is twice the height times the width. The size of the triangles that are removed is equal the square of the size (along the side of the rectangle). Because there are two corners, the combination of values that can be substracted increases with a power of two by the smallest height or width. Thirtheen is the first number, where there all the combinations are sufficient. Or in other words, for each number from 336 and above, there is a rectangle of height thirteen and a width equal or larger than thirteen with some corners removed with the required number of triangles. I wrote a program to verify this.


Wednesday, February 6, 2019

Steered by technology

This evening, I went to Tetem art space to listen to the talk Gestuurd door techniek: Meegaan of weerstand bieden? (Steered by technology: Go with it or resist it?) by Peter-Paul Verbeek. The talk started a little late. (I wrote the following during the talk. It is my intepretation of what the speaker said.) Yesterday there was a news item about parents tracking children (through their mobile phones). It turned out that actually quite a number of parents are doing this. Parents think that it is go to use this technology. Another example is how people are always on their smartphone. There were also technology designed to steer us, such as speed cameras. There are also people against them and even destroy them. But these people do not realize that the roads are also designed in such a way that they control our behaviour. Why we do not design cars such that they cannot drive too fast. Probably, many people would be against this, because they would feel that it limits their autonomy. Speed bumps are also designed to change our behaviour: to make us brake our speed. Nowadays, we have the problem with fake news. Social media have started to control our thoughts. The first industrial revolution was the first large scale experiment with technology. Marx realized how this was tied in with capitalism. The movie Modern Times wanted to show that technology is steering people: how people become slaves of the machines. Currently, we are said to be in the fourth industrial revolution. Now there are also people who are against it. What is a stake now? We would like to split the world into subjects and objects. But maybe it is not possible to make such a clear a cut. Probably, they are always intertwinned. We create technology, but technology also change us. Technologies are often used for moralisation. Hans Achterhuis came with the proposal to moralisation of machines. People critized him about this. But that this week, there was a very big traffic accident on the high way due to heavy fog. The book Nudge by Richard H. Thaler and Cass R. Sunstein. 80% of the choices we make are habits. Maybe only 10% of our choices are conscious choices. There are very subtile ways to influence the behaviour of people. Persuasive Technology by B.J. Fogg. To use technology to persuate you in a certain direction. About autonomy. Technology is so much a part of our life, that we cannot escape it. Think, for example, think about the birth controll pill. It has had such an influence on our ethics. Kant said that the three big questions are: What can I know? What should I do? And what can I hope for? Technology has given us some answers on these questions. Steven Dorrestijn said that technologies work in four areas: Before the eye (persuasion, suggestion), to the hand (coercion, mediated gestures), behind the back (trends, user configuration), and above the head (utopian technology, dystopian technology). There are two axes about influence: from hidden to apparent and from weak to strong. Resulting in four quadrants: Coercive, persuasive, seduction, and decisive. The last is maybe the most scarry. Design mediations. You have a social goal: you want to have some desired behaviour. From this you have to design technology that encourage this behaviour. Design for environmental behaviour. Some one form Taiwan made him realize how much we here in the West are attached to our autonomy, even if it is clear that in the future it will destroy our world and make autonomoy completely irrelevant.

After the talk, I made some mention of the book On Photography by Susan Sontag to the speaker. Afterwards, I found it a pitty that the speaker did not address the possible impact of AI on our lives in the coming twenty years.

Björn Zielman

I went to the opening of the exhibition of Björn Zielman at B93. His exhibition also contained paintings by his mother Lammie and sculptures by his aunt Nancy. I also met with two of the members of Heliophile. One of them, under the artist name AcheFace, gave a performance on a modular synthesizer. I also met some other people and talked with them. I stayed for about an hour.

Thursday, February 7, 2019


This evening, I went to see the exhibition I owned a tree by Linda Vilka at the Tankstation in Enschede. Later, I also went to Concordia and saw the exhibition Inktspot of a hunderd political cartoons from Dutch newspapers. I also played a little with some musical art works that are part of the exhibition Ik zie ik zie wat jij niet hoort (I see what you do not hear), which is geared towards children.

Friday, February 8, 2019

Memoral service Martin Medema

Yesterday, I got news that Martin Medema died during the night of Monday to Tuesday and that there would be a short memoral service this morning. I doubted a long time whether I should go, because it was on Friday, June 12, 2009 that I met him for the last time. I met him shortly after I arrived at the University of Twente, usually at (board) game club Fanaat. I am happy that I did go. I discovered that until recently (when he became ill), he was a frequent guest at Fanaat. Almost half of the attendees where current members of Fanaat, students of the University. But there were also some people from the early eighties, some of which had not seen Martin for much longer than me. Arjan and Erik, as long time members of Fanaat, also attended. (The only person, I had expected to see, did not come.) Someone from the eighties had brought a seven hexes segment and placed it on the coffin with six wooden round stones of different colour on top of it. These are used in the game Atlantis. After the nephew of Martin said some words, several other people said some words, often telling how Martin had taught them important lessons in life, about trusting and living an alternative, nomadic life-style.

Saturday, February 10, 2019


I have installed Unbutu on johan. I installed it on the disconnected hard-drive that I put in place as an anti-virus back-up. It appeared that this drive was also seen as the first drive. So, now johan is a dual-bootable PC. I noticed that Firefox does not run very smooth under Unbutu and that it having similar problems with playing videos, like it has under Windows XP. I would think that it is related to my graphics card not being fully supported anymore.

Wednesday, February 13, 2019


Last Monday, I came across the China Labyrinth and the Octopuszle. Yesterday, I wrote a program to generate an Exact Cover for this problem and last night I ran my Exact Cover solver on it, but it did not find any solutions. Today, I discovered that others tried it before and did find solutions using a Python 3 Exact Cover solver. This was also refered to in a Hacker News thread about Organicity in abstract strategy games. Anneke Treep discussed it in the March and July 1990 issues of Cubism For Fun newsletter.

Thursday, February 14, 2019

Exact Cover to SAT

Thinking about the Octopluszle and the lack of succes of making any progress, I decided to see if converting the problem into a Boolean satisfiability problem would be an option, knowing that there is a lot of research going on SAT solvers. I came across Solving Exact Cover via SAT, which happens to be from the same person who tried to solve the Octopuszle with an Exact Cover solver almost a year before. We could conclude from this, that he did not make much progress and that the Octopuszle is indeed a very hard puzzle.

Saturday, February 16, 2019

Come together in a dream

I went to the opening of the exhibition Come together in a dream by Emmy Zwagers at XPO. I liked her work acryl op paper 300x400 2017. I understand that for her the process of making the work is as important as the result.

Tuesday, February 19, 2019

Octopuszle 4x4

Yesterday, I got an idea for finding solutions for the Octopuszle. The idea is to split the large puzzle in four by four smaller puzzles. If you look at only the horizontal and vertical lines, then there are 652 solutions of all possible pieces within four by four pieces. I discovered that there are no solutions when you only look at the diagonal lines. This night, I ran the Exact Cover solver to figure out how many solutions there are for filling a four by four square with all of the pieces, such that there is exactly all the pieces are used when ignoring the diagonals. The answer was 170,917,888. Today, while biking, I concluded that there might not by any solution at all, simply because of the pieces that are needed at the border. Not suprisingly, 170,917,888 is equal to 652 times two to the power 18. I have no idea how to proceed from here.

Thursday, February 21, 2019

Alita: Battle Angel

Annabel and I went to see the movie Alita: Battle Angel. We both did not have high expectations of this movie, but we both enjoyed it very much hoping that a sequel will be made soon.

Tuesday, February 26, 2019

Hexagon numbers

This afternoon, I thought about the hexagon numbers not with triangles but with hexagons on the corners of the triangles. That is because I wanted to know if there is a hexagon with 64 smaller hexagons. If every side should have more than one hexagon, the smallest configuration you can create, consists of seven hexagon. The following sizes, above seven, are not possible: 8, 9, 11, 15, and 17. There are several ways to make a hexagon with 64 hexagons and the most round shape seems to have sides of lengths going round: four, seven, four, five, six and five.

19.2° Celsius

This morning, between seven and eight, the temperature was still around -1° Celsius, but around four in afternoon, it reached 19.2° Celsius. Very likely a record, probably also for the whole month of February.

This months interesting links

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