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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.

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 was 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. On the right a picture of the inside.

Saturday, September 30, 2017

Brain machine

Last week, I bought the following parts from STORES for the brain machine:
  • 10K potmeter with nob
  • 2m 3.5 jack extention cord
  • Two 3.5 female jacks
  • Three 220Ω resistors
  • Two 3.3KΩ resistors
  • Two 1µF elco condenstators
  • Two red 5mm LEDs
  • Small box including PCB
This afternoon, I spend about four hours working at TkkrLab at assembling the brain machine. I spend some time removing some material from the PCB of the Arduino Nano near the USB connector with a file, to make it fit in the box. Next I spend some time putting the components on the PCB. I also attached some wires (not all) that will connect to the jacks, the potmeter and the reset button on the top part of the box. Below a picture of the PCB in the box, where I added some red lines to indicate how the components are connected on the back, and a picture of the back of the PCB.


Friday, September 29, 2017

885 solutions for 10 with 22 integers

While one program is still working on finding solutions for the the Irregular Chocolate Bar problem for up to and including 9 equal divisions, I decided to also start a run for up to and including 10. To my surprise it found 885 solutions with 22 integers. It is possible that there are solutions with 21 integers. The 'smallest' of the 885 solutions, with respect to the integers used, is:
17 45 52 53 80 81 95 96 105 108 109 111 115 116 136 137 143 144 171 172

Thursday, September 28, 2017

105869 solutions

The program for the Irregular Chocolate Bar problem for up to and including 9 equal divisions has found 105869 solutions with 20 integers starting with three 'chains' and two additional cuts. A 'chain' is a sequence of integers, where each pair of consecutive interers add up to alternating 280 and 315. It is now working on starting with a 'necklage' and three additional cuts, but has not found any solutions yet. It would not surprise me, if it does not find any aditional solutions. I checked if any of the solutions could be divided into 10 equal divisions, but this was not the case. Below the 'smallest' solution is given, with respect to the integers being used.
31 60 80 85 95 99 109 111 115 120 121 124 150 156 159 160 165 185 195 200

Tuesday, September 26, 2017


It is clear that the fall has started. I saw some very large mushrooms along the road. At 10:21, I picked up six big chestnuts from a tree on the Hengelosestraat near number 569. There were many more on the ground.

Brain machine

A friend of mine wanted to have a brain machine like the one offered by Ada Fruit, but when it turned out that the international shipping costs were rather high, I decided to build one myself from parts. I started with the design by Chris Sparnicht and took some ideas from the brain machine from Ada Fruit with respect to the schematics of the headphone. I also decided to use a single potmeter to control the volume by putting it between the 'ground' of the earphones and the ground. I am aware that this could cause some crosstalk when the volume is reduced, but I hope it is not going to be a big problem. While at TkkrLab, I arrived at the principal schema as displayed on the right and made a shopping list of parts. I bought a cheap Arduino Nano clone from the stock at TkkrLab.

Friday, September 22, 2017

Solutions for 9

In the past month I have been thinking about an alternative algorithm to tackle the Irregular Chocolate Bar problem, but it has failed to materialize. This week, I decided to see if I could improve on the existing algorithm to get at least some solutions. It is always nice if you can limited you search space by an upper limit. I started the program yesterday afternoon and by the end of this evening, it already found over fifty thousand solutions with 20 integers. This makes me wonder if there is a solution with 19 integers. These solutions are found by constructing a 'chains' solution for 18 integers and then twice split an integer into two. The improvement on the algorithm is that it first performs some check on the solutions for 18 integers with an alternative knapsack algoritm to see if it possibly could contain a solution with some additional splitting, before trying all possible splits and testing them against the existing algoritm. The first solution found by the program is:
1 6 29 41 45 60 80 81 95 115 130 150 154 165 185 200 210 220 274 279

Saturday, September 16, 2017


I went to the opening of the exhibition Wegzeichen with works by Carina Schüring organized by Kunstverein Vreden. Bernd Sikora gave an introduction. Although it was in German, I had no problem with understanding it. Although I had seen the work recreating familiarity last year, I appreciated it much more than I can remember, probably because of how it is exhibited. I also like her work embracing insecurity. It was also nice to see the drawing Alles (Everything) again. I also bought Carina Schüring Portfolio 2017 with a introduction by Arjan van Helmond from her for € 35.00. (One of three copies as I found out after I bought it.)

Heliophile & Voltmeister Modular

In the evening, I went to a live performance of Heliophile for their debut CD Permeate. Before their performance, there was a performance of Voltmeister Modular. I bought the CD and listened to it at home.

Sunday, September 10, 2017

Gogbot: Day 4

I went with Andy to the former Coberco milk factory to see the Gogbot exhibitions there. The most interesting was a tapered kaleidoscope. I took several pictures inside it, one of which is shown here to the right. The other exhibits that I found worth mentioning are:

The Truth

Finished reading the book The Truth: An Uncomfortable Book About Relationships by Neils Strauss, which I started reading on September 2, the day after I bought it. This book continues where his book The Game, which I read in July, ended and is even more interesting and thought provoking than that book. I very much enjoyed reading this book and it realy made me think about my own life.

Saturday, September 9, 2017

Gogbot: Day 3

Together with Andy, I visited TETEM art space, where we walked around and saw Spectra by Matthijs Munnik. The effect of seeing all kinds of colours in a blinking light is familiar to me. Still interesting to see it.

Friday, September 8, 2017

Gogbot: Day 2

It was a rainly day. For most of the afternoon and the evening, I stayed at TkkrLab stand at Gogbot. During the relatieve quiet afternoon, I build a Creep Cluster by Reverselandfil and in the evening, I joined them with their noise performance on the stage on the square for a quarter of an hour. I looked around in the Grote Kerk and saw: A thing and its essence by Joseph Klibansky, Phyllotaxis by Daan Johan and Joris Strijbos, and works by Freek Wieringa. At Concordia, I saw Cogito by Daniela de Paulis and Fractal Shorts by Julius Horsthuis. At Menistenkerk, I had my brain 'scanned' with The Brainlight by Laura Jade. I also saw Superpower Studio by Dominica Chen (which I already at seen at the Rietveld Academie on July 9, 2017 ) and I looked at a Beowulf cluster of 37 Rasperry Pi's. At the end of the evening, there was another performance by Empress Stah, this time before the church in a transparend sphere.

Thursday, September 7, 2017


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