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I write, therefore I am

With this variation on a famous statement by the philosopher Descartes, I would like to express that the act of writing about what happens in my life is important to me.

Tuesday, November 21, 2017

HEMA puzzle

Last month, I calculated the number of solutions for the HEMA puzzle, but what I had not taken into accound, was the fact that some of the wooden pieces of the actual puzzle do not fit, simply because the part that should fit in a 'gap' of another piece, is not small enough to fit. I made some analyses of all the possible combinations of pieces that require a physical constraint in all the solutions (using this program) and added that information below. I named the pieces according to the names given by Name that Color. You can indicate which of the pieces do not fit and see which solutions you can actually make. The initial values are for the my instance of the puzzle.

Patina fits Chestnut
Sahara fits Chestnut
Madison fits Chestnut
Victoria fits Chestnut
Amazon fits Chestnut
Arm of Kimberly fits Chestnut
Stem of Kimberly fits Chestnut

Victoria fits Sahara
Amazon fits Sahara
Tabasco fits Sahara
Arm of Kimberly fits Sahara

Arms of Kimberly fit Chestnut and Sahara

Chestnut fits Madison
Patina and Victoria fit Madison
Highland fits Madison
Raw Sienna and arm of Kimberly fit Madison
Victoria and arm of Kimberly fit Madison
Amazon fits Madison

This text is displayed if your browser does not support HTML5 Canvas.


Saturday, November 18, 2017

Open day AKI

In the afternoon, I went to the AKI. Outside I ran into a friend, who in the past studied at the AKI. We decided to attend the open day together. First we went to the media center and library. Outside there was a table where the sold old catalogues for € 5. At 14:04, I bought the following two catalogues: At the photography department we looked inside the dark room, and the friend took a picture of me with the 8x10 camera on photographic paper. We went to dark room again, to see how it was developed. While it was being rinsed, we looked around the students rooms with paintings and other works of art. We did see some promissing work, but because the students were not pressent, it was not possible to talk with them. When the photograph was ready, it was scanned and I received a print (after it inverted). Two teachers were posing and giving assignments. I also made two 'drawings' with a brush and indian ink. I took some pictures of the teachers, especially when they were performing a slow motion dance. At the end we had our picture near the entrance holding a frame with the text: AKI OPEN.

Thursday, November 16, 2017


Monday, November 13, 2017

Bike stolen

At 17:30, I arrived at charity shop Het Goed and looked around the book section. When I came outside around 17:50, my Urban HPV bike, which I got on Wednesday, March 9, 2011, was gone. I spend some time looking around, considering the possibility that I was mistaken about the place wheren I had placed it. I went inside to ask if it happens more often that bikes are stolen in front of the shop. They had only heard about an electric assisted bike being stolen. The bike was already getting old, but at the beginning of the summer the transmission had broken down and was replaced by a new one. I was counting on using it for another three years before it being replaced. I have not much hope of getting the bike back, as usually they are transported to East Europe and sold there. I did report the bike as being stolen when I arrived at home. I will miss all the extra things: The two horns (on a gift from Annabel, the other found in the attic), the three induction lights, and the two yellow CYBER stickers.

Sunday, November 12, 2017

Infinite sequences

I discovered that my statement about street tiling pattern of the first of the month is incorrect. When I increased the length of the sequences to be investigated, I discovered that it did not stop at what I had thought. It seems the list of impossible sequences and chains is infinite. (A chain consists of two sequences that match with valid tiles.) I studied the impossible sequences for a general pattern, but did not discover one. I did noticed that sequences and chains where not really symmetric and realized that this has to do with the encoding method of the street tiles, which all start with an 'A' in the left top corner. This gave me the idea to give eacht street tile its own encoding letters, using the following encoding:
  a bc

  d fg jkl
  e hi mno

    pq ABC
    rs DEF
    tu GHI
This resulted in only a limited set of chains (only with length two) to be impossible. But it seems that there are still infinite impossible sequences. I started visualzing the sequences with embedded JavaScript below and only leaving the characteristic sequences:
This text is displayed if your browser does not support HTML5 Canvas.

It looks that for each length, there are only a limited number of patterns, if we look at the the depth at which the piece extend down. I have selected one pattern for each of them. I also worked on constructing grammar (so far only a regular expression) to match all the patterns.

Friday, November 10, 2017


Thurday, November 9, 2017


Tuesday, November 7, 2017

Bottle ring

This evening at TkkrLab, another member made a bottle ring with the text ffaa5e with the of Blender and one of our 3D printers. The result is show on the top right.

Monday, November 6, 2017

Walking Through Walls

Early this morning, I finished reading the book Walk Through Walls: A Memoir by Marina Abramović and James Kaplan (as ghost writer, it seems), which I started reading on October 14 after I bought it on October 11. I actually really started reading the book from October 24. I found this quite an interesting book, mind blowing at moments. It made me also realize how much I already knew about her, first through the book The lovers, which I bought many years ago and also read, and later also through watching some videos about her and her performances. She also talks about her personal struggles and the many retreats she undertook remote areas, with Australian Aboriginal peoples, at buddhist monastries, and with shamans in the amazone. Many of these she describes as life changing. She also descibes her struggles when her second husband Paolo Canevari leaves her, actually twice, to a women who described herself as a sexual anthropologist, a woman with dead-white skin and red hair. Betony Vernon matches this description and there are also photos of her together with Paolo Canevari. However, from 2004 to 2014, Vernon was married to Barnaba Fornasetti. Canevari met with the woman at the Givenchy show in 2008 and in 2010, Abramović talked with the woman against the will of Canevari after he had returned to her. The woman told her: "He's addicted to me. He will always come back to me." And that is what happened. Probably the woman understood male sexuality better than Abramović, that she could make this statement.


Wednesday, November 1, 2017

Are street tiling patterns Turing complete?

Today it is 56 calendar years ago that I was born, which means that I am born on a Wednesday. This is because 56 is twice 28 and it is a property of the Gregorian calendar that the days of the week repeat after 28 years (except when there is a century crossing involved that is not divisible by 400). I did not really celebrate my birthday.

Last week, I wondered whether it is possible to generate a possible infinite street tiling pattern without using back-tracking. I thought about starting with some row of a certain length and next generate rows below it as long as I wished. I was thinking about putting this into a JavaScript script inside a page and generate a random pattern on demand. I worked on a program to generate all impossible sequences to be found in a row and all impossible continuations from a part of a row to the next row. I think the program is correct, but I do not know how to convert the output into a state machine for generating a 'random' row below a given row. I even do not know if it is possible. Than it appeared to me that maybe Street tile patterns might be complex enough to be Turing complete.

Monday, October 30, 2017


Sunday, October 29, 2017

Overkill Festival

This weekend, I attended the Overkill Festival held in Enschede. I would like to mention the following art works and games which I liked: I spend most of my time with the people organizing the Alzheimer GameJam, who are from Conceptlicious Games and Breath Audio.

Friday, October 27, 2017

HEMA puzzle

In the evening, I went to the Overkill festival and there I found a little wooden puzzle sold by the Dutch shop HEMA. Of course, I wanted to know the number of solutions. I wrote the following geometric puzzle representation for the puzzle:
2 0
 0 0  0 1  0 2  0 3  0 4  0 5  0 6  0 7
 1 0  1 1  1 2  1 3  1 4  1 5  1 6  1 7
 2 0  2 1  2 2  2 3  2 4  2 5  2 6  2 7
 3 0  3 1  3 2  3 3  3 4  3 5  3 6  3 7
 4 0  4 1  4 2  4 3  4 4  4 5  4 6  4 7
 5 0  5 1  5 2  5 3  5 4  5 5  5 6  5 7
 6 0  6 1  6 2  6 3  6 4  6 5  6 6  6 7
 7 0  7 1  7 2  7 3  7 4  7 5  7 6  7 7
 8 1    0 0  0 1  0 2  0 3  1 0  1 1  1 3  2 3
 7 3    0 0  0 1  0 2  1 0  1 1  2 0  2 1
 7 3    0 0  0 1  1 0  1 1  1 2  2 1  2 2
 6 3    0 0  0 2  1 0  1 1  1 2  2 2
 6 3    0 0  0 1  0 2  0 3  1 0  1 3
 5 3    0 0  0 1  0 2  1 0  2 0
 5 3    0 0  0 1  0 2  0 3  1 0
 5 3    0 0  0 1  0 2  1 0  1 1
 5 3    0 1  1 0  1 1  1 2  2 1
 5 3    0 1  0 2  1 0  1 1  2 0
 5 3    0 0  0 1  0 2  1 1  2 1
I piped this through gen_dpfp and dpfp2ec into my Exact Cover solver. It found 89 solutions, which can be viewed below:

This text is displayed if your browser does not support HTML5 Canvas.


Tuesday, October 24, 2017

Girl in a Band

This morning, I finished reading the memoir Girl in a Band by Kim Gordon, which I started reading on the first of the month. I bought the book on Saturday, July 22 when I was in The Hague. I had never heard from her before nor heard any of her music, and I also did not follow the music scene and all that is related to it, so I could not really appreciate all the details with respect to her music and the people she worked with, although some of the names are familiary to me. (I am often surprised that so many famous people have met and know eachother.) Nevertheless, I found it an interesting book to read, because she seems to talk very open and honestly about her life, as if she could have been a woman with a normal job.

Tuesday, October 17, 2017


Monday, October 16, 2017


Sunday, October 15, 2017


Wednesday, October 11, 2017


At 17:35:03, I bought the book Walk Through Walls: A Memoir written by Marina Abramović in English and published by Penguin UK in 2016, ISBN:9780241974513, from bookshop Broekhuis for € 14.99.

Tuesday, October 10, 2017

Reprogramming brain machine

This evening at TkkrLab, I looked at the code (based on Arduino_Brain_Machine.pde) of the brain machine. I had noticed that at the end the LEDs where left switched on. I discovered that the schematics had the LEDs connected to the positive voltage, where I had connected them to the ground. I asked someone about whether this was a problem and I understood that connecting the LEDs to positive voltage may make them brighter. I also modified the sequence of blinking frequences, removing the gamma waves that interleaved the delta was in the middle. I discovered that the reset button does work, but that it was only used to restart the sequence after it had completed after it had started on power-up. I changed it in such a way that the sequence does not start on power-up, but that the button has to be used to start the sequence and that the button can also be used to stop the sequence once it is running. This resulted in the following BrainMachine.ino.

Monday, October 9, 2017


Sunday, October 8, 2017

Finishing brain machine

Last Friday, I installed Arduino on netbook, downloaded the Tone library and compiled the Arduino_Brain_Machine.pde file and uploaded it to the brain machine. The day before, I already had realized that the volume control might not going to work as designed and that I might have to add two diodes to fix that. And indeed the volume control did not work. I noticed that it immediately started to make sounds after I had plugged in the power and that the reset button did not work. I also verified that the LED part was working. Today, I finished the glasses with the LEDs and tested the device. I noticed that the LEDs were less bright than the brain machine from Ada Fruit, but that it did not really change the experience once you have adjusted to it. I also noticed that the potmeter did influence the quality of the sound. So now I doubt if I should fix it. On the right a picture of the finished box and glasses, which I decorated with the paper from the Ada Fruit brain machine.

Thursday, October 5, 2017


I found a simple proof for yesterdays conjecture, which is related to the Irregular Chocolate Bar problem.

Theorem: For each natural number n (larger than three) there exists a set of 2n-1 (distinct) natural number that sum up to 3n(n-1), such that there exists partition of size n and n-1 sets, where the numbers in each set of the two partition sum up to 3(n-1) and 3n respectively.

Proof: For given n, the show the construction of the set. First of all, it includes 3(n-1). Next, 1 is added to the set and also 3(n-1)-1, such that they add up to 3(n-1). Now there, must also a number that together with 3(n-1)-1 adds up to 3n. This is the number 4. And that lead to the number 3(n-1)-4 that needs to be included. Continueing this process, will finally lead to the number 3(n-1)-(3(n-2)+1), which is equal to 2. The numbers 1 and 2 together with 3(n-1) add up to 3n. We also have another n-2 pairs that up to 3n. That makes a total of n-1 pairs that add up to 3n. Besides the number 3(n-1) there are also n-1 pairs that add up to that number, making total of n sets (one with only one element) that up to 3(n-1). This completes the proof. Notice that the constructed set comes down to the set {1, 2, 4, 5, .., 3(n-1)-2, 3(n-1)-1, 3(n-1)}.

Wednesday, October 4, 2017


I propose the following conjecture: For each natural number n (larger than three) there exists a set of 2n-1 (distinct) natural number that sum up to m, which is a multiple of n(n-1), such that there exists partition of size n and n-1 sets, where the numbers in each set of the two partition sum up to m/n and m/(n-1) respectively.

Tuesday, October 3, 2017

Wiring brain machine

This evening at TkkrLab, I continued working on the brain machine. I drilled holes in the box for the jacks, the potmeter and the reset button. I wired these to the PCB. On the right a picture of the inside.

Saturday, September 30, 2017


November 2017
October 2017
September 2017
August 2017
July 2017
Alzheimer's Disease
Trip to China 2010
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