Dutch / Nederlands
Site map

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, May 19, 2019

Square Wave

I went to the Square Wave - Modular Synt Improv Meet in Deventer, which was organized by Voltmeister. Eight people had shown up with their (modular) synthesizer. During every round, they were paired up by a draw for doing a synthesizer improvisation given a BPM selected at random. I am thinking about starting with modular synthesizers myself. Around 2003, I played with various software synthesizers. For example: SynFactory. In the past weeks, I did some investigation with respect to the various formats and directions there are with respect to modular synthesizers. I getting more and more excited about the Eurorack format.

Thursday, May 16, 2019

PlanetArt reopening

I went to the reopening of PlanetArt in Enschede. They are, besides many other things, the organizers of the GogBot festival. I met various people that I know to different degrees. There were also a lot of people that I do not know. I had some interesting conversations and decided to write this while being there. I decided not to stay too long.

Tuesday, May 14, 2019


At 16:45, I received the book Jaarboek 09|10 written by Ina Bodde, Marion Bouwhuis, Ina Klaassen, Coen Scheen, and Petra Winkes, in Dutch and English, published by ArtEZ Art & Design in 2010, ISBN:9789075522358, which I had bought on Wednesday, May 1, 2019 at 19:22 from AKI shop for € 25.00. At 17:46, I bought the following three books from charity shop Het Goed:
  • FastFurniture, Multiples and Other Productions written by P.J.H. Kockelkoren in English and Dutch, published by Uitgeverij AKI/ArtEZ in January 2007, ISBN:9789073025103, for € 1.50. (Later, I discovered, that I already have this book.)
  • Fluid Fascinations - Visualisatie written by Martha J. Haveman, Onno Bokhove, and Valerie Zwart, written in Dutch and English and published by Qua Art - Qua Science in April 2010.
  • Art is therapy written by Alain De Botton and John Armstrong, written in Dutch and English and published by Rijksmuseum in 2014, ISBN:9789491714382.

Sunday, May 12, 2019

Open air book market Tuindorp

In the morning, I went to the open air book market Tuindorp in Hengelo. At 11:43, I bought the book Het litteken van de dood: de biografie van Jan Wolkers written by Onno Blom in Dutch and published by Bezige Bij in 2017, ISBN:9789023468721, from Ruco Pesse for € 14.59.

Saturday, May 11, 2019


Tuesday, May 7, 2019

Pythagorean primes

I spend some time researching the conjecture, which I described on last Thursday. First of all, I discovered that the relationship that I described has been known (in a slightly different form) for centuries and is known as the Brahmagupta-Fibonacci identity. I also have discovered that it seems that numbers n are always the product of Pythagorean primes. Fermat's theorem on sums of two squares states that prime number can be written as the sum of two squares if and only if it is a Pythagorean prime (proof). Combining the two, it is also clear that there is only one way in which a Pythagorean prime can be described as the sum of two squares. If there were two (or more) ways, than you can find two numbers that are the sum of two squares, which when multiplied are equal to the prime, which would be a contradition. It seems also rather obvious that the product of two different Pythagorean primes must have two ways it can be written as the sum of two squares. Although the reverse also seems likely, the proof for it seems a little more complicated. It is clear that the product of two primes, can only written in one way as the product of two numbers (where the first is smaller or equal to the second).

Sunday, May 5, 2019


At Concordia, I saw the exhibitions Le Gymnasium Sacre by Sam Samiee and Grenzeloos with works from the four Dutch artists Ronald de Bloeme, William Engelen, Jeroen Jacobs and Maarten Janssen, who (independenlty of eachother) moved to Berlin.

Thursday, May 2, 2019

Sum of squares

A friend of mine pointed out that it seems that if a odd number can be written as the sum of n pairs of squares (and the greatest common divider of all these squares is one), that the number can be written as the product of n-1 different pairs of numbers. The numbers in these pairs are sums of squares as well. I do not know if this is a know fact, but it seems to be true for all such numbers up to a million (as verified with this program). Today, I proved that for any two pairs of squares that add to the same number, there exists (at least one) product of two sums of two squares that results in the same number. If the sum of squares is odd, one of the squares must be odd and the other even. In that case, match the odd and even squares of both pairs. In all other cases either both squares are even or odd. In which any matching will work. Now given: ai2 + bi2 = aj2 + bj2 = n, assume that ai is smaller than aj (and that the match with respect to oddity/evenness). There exist whole numbers c, d, e, and f such that: ai = c - d, aj = c + d, bi = e + f, and bj = e - f. Through subsitution, one can show that: c2 + d2 + e2 + f2 = n and c.d = e.f. Furthermore, one can define q, r, s, and t, as follows: q = gcd(d, f), r = gcd(c, e), s = f/q = c/r, and t = d/q = e/r. For which one can show that: (q2 + r2)(s2 + t2) = n.

Wednesday, May 1, 2019

Factotum - WYDSIWYG

I went to the opening of the exhibition Factotum - WYDSIWYG by the photographer René Damen at B93. The exhibition was opened by Jeffrey Pardoen through a video connection from England. Factotum is Latin for Jack-of-all-traits and it does describe the exhibition well. The photographs are group together in interesting combinations, which are not always obvious on first sight. Sometimes, they resemble in colour, sometimes they resemble in shape, and sometimes they resemble in little details. This has indeed something poetical as Pardoen said during the opening speech.


Monday, April 29, 2019

Other Places

In the evening, I had a quick look at the exhibition Other Places at the University of Twente. I found the works by Judith Schepers most impressive.


Sunday, April 28, 2019


Saturday, April 27, 2019


Thursday, April 25, 2019

Mapping Minimalism

I went to the opening of the exhibition Post-War and Contemporary Art at Christie's Amsterdam preceding the auction, which contains four works by Peter Struycken. During the opening, Carel Blotkamp gave the lecture: Mapping Minimalism - Galerie Riekje Swart and her network. (The following is based on notes I made during the lecture. It does not cover everything being presented.) Blotkamp remarked that you could do a PhD on this subject. In the sixties he started to visited galeries. When he finished his studies, he became a art critic besides his position at the university. In the sixties, the Dutch museums were very active and this was also recognized international. They were actively searching for new talents and had a leading role in this regard. Now this is now no longer the case. Willem Sandberg, the directory of Stedelijk Museum, was the driving force behind this. In 1938. he curated an exhibition about abstract art. In 1958 he wrote a statement about how the museums should be open to current art. The media were rather critical about this. But he did not only focus on recent art. For example, in the same year, he also organized an exhibition about Jackson Pollock. He had high regards of the COBRA movement. In 1962 he organized the exhibition nederlands bijdrage (The Dutch contribution to the art since 1940), which included many works from Dutch members of the COBRA movement. In the Netherlands there were also artists who opposed the COBRA movement. In 1962 the exposition nul was held with works from ZERO artists. Sandberg was followed by Eduard de Wilde, who organized an exhibition about PopArt. The exhibitions in Dutch museuma followed recent decelopments, much faster than American museums. (Blotkamp showed a picture taken at an exhibition with Jan Wolkers in it.) The Stedelijk Museum bought the boat made by Yayoi Kusama, which is now regarded as one of the most important works from that period. The poster of the exhibition vormen van de kleur (shapes of colour) mentions minimal art. (Blotkamp showed a picture with Bob Bonies in the exhibition.) Around that time, The Van Abbemuseum in Eindhoven, lead by Jean Leering, started to focus more on minimal art. In 1968 there was a large exhibition with works from American artists at Gemeentemuseum Den Haag. This was followed by a exhibition in the Stedelijk Museum about minimal and conceptual art. An influencial art magazin from this period was Kunst & Museumjournaal. Newspapers were still rather negative about these art developments. The galleries played a small role. The Dutch market was too small for galleries to get works from foreign artists. But also the galleries became good at scouting new talents. Most of these galleries where in Amsterdam, but there were also a number of significant galleries elsewhere. Riekje Swart, quited her regular job, and opened her gallery in 1964. (Shows a picture of her before two works by Peter Struycken: Komputerstrukturen 3a and Komputerstrukturen 3.) It was only in the second year that she focussed more on geometric art. Ad Dekkers and Peter Struycken had exhibitions with her. (Shows picture with Ad Dekkers, Hans Koetsier, Bob Bonies, Peter Struycken and her, with one work by Ad Dekkers and two works by Peter Struycken visible in the backgound: Structuur XXXV - 67 and Structuur XXXII - 67.) They were different artist but all had something with geometry. She also had conceptual artists, such as: Ger van Elk, Jan Dibbits and Marinus Boezem. Some of these artist got large solo exhibitions in and outside The Netherlands. In 1968 the exhibiton junge kunst aus holand in Kunsthalle Bern showed works of 21 artist. Eight of these were from Riekje Swart, which is quite remarkable, because her gallery just had opened for four years. She continued to be focussed on geometric art. Riekje Swart also exchanged works with some galleries in countries around The Netherlands. Riekje Swart was not good in selling works, but she had a very loyal circle of customers, mostly from the middle class as the very rich did not invest in modern art. The exhibition Three blind mice: de collecties: Visser, Peeters, Becht was an important exhibition with works from private collectors. Other Important collectors were Jo and Marlies Eyck and Geert van Beijeren and Adriaan van Ravesteijn (who later started Art & Project). Jan and Tieneke Hoekstra also made part of this. (Their collection is part of the auction.) Although they collected works from various artists, their collection shows a remarkable consistency. Frans Haks played an important role in the later development of the gallery.

After the lecture, I watched the works on display. I found the following works notable (in order of their catalogue number):

  • 2 Trames 0°, 90° (intervalles 14 cm et 17 cm) by François Morellet. (nr. 51)
  • V70-27B by Herman de Vries. (nr. 57)
  • Structuur II by Peter Struycken. (nr. 60)
  • random structures: an essay by Herman de Vries. (nr 101)
Someone arranged a hard-copy of the catalogue for me.

Wednesday, April 24, 2019


At 15:38, I bought the book Handreiking beeldende kunst in de openbare ruimte edited by Jan Brand, written in Dutch and published by Cultuurfonds BNG in 2000, ISBN:9032279181, from charity shop Het Goed for € 1.50.

Friday, April 19, 2019

Two books in cassette

At 13:09, I bought the book Ovidius Metamorphosen - Munkedals Voorbeelden (two books in a cassette) with a forword by Nova Rese and part of the Dutch translation by M. d'Hane-Scheltema of the text Metamorphoseon libri by Ovid written in Latin, from charity shop Het Goed for € 7.50.

Thursday, April 18, 2019

Decentralized web

I went to a presentation about the decentralized web given by two people from Muze, the developers of SimplyEdit (the first CMS designed for the decentralized web) and SimplyView. The decentralized web is seen as a solution for linkrot, congestion (also due to DDoS attacks), and vendor lock-in. It does not solve problems with privacy and control. The decentralized web is not the same as blockchain, although some implementations make use of blockchain technology. The centralized web is based on peer-to-peer node networks. This makes the browser into a server as well. More and more often the browser is becoming the OS, which is, for example, seen in the development of progressive web applications. Some decentralized web technologies are:


I saw the exhibition Windstilte with works by Manje Dijkman at Bookshop Broekhuis. The exhibtion contains portrets but also some landscapes consisting of two pannels, where the top one represents the sky. I saw the exhibition Living Landscape by Marloes Staal at XPO. The guests where sitting outside because of the nice weather and I talked a bit with some of them.

Bioart's engagement with life

In the evening, I went to Tetem artspace for the talk/workshop Bioart's engagement with life by Lotte Pet. She is an artist, studied art and now doing an PhD in which she researches art as a means to gain knowledge within scientific and technological discourse. (The following is based on notes I took during the talk.)

Biotechnology is the manipulation of living organisms or their components to produce usefull usually commercial products. Currently, a lot of research is done with applications to health care. But there are also big ethical issues involved. Biotechnology is not neutral. The application of it has an impact on our culture and how we value things. It changes our opinions. A recent example is story of two Chinese babies, whoes DNA was modified with CRISPR/Cas9 in order to make them resistent for HIV. But it also might have improve their intelligence. Should we improve humans? Does increasing intelligence improve humans? But also direct-to-customer genetic testing has implications. The cheapest form is genotyping: telling you something about your ancestory. Another form is whole-genome sequencing, which allows to find for genetic defects that are associated with certain health risks. And than there are also issues with the storage of DNA profiles, which could be used for other purposes. Take, for example, the case of the Golden State Killer. (I made a remark about the impact of prenatal testing.) In the end it all comes down to the question: What does it mean to be human?

BioArt is a contemporary art practice started late 20th century. There are two means: Representational tactic (art presenting the results of the application of biotech) and presentational tactic (art created through the application of biotech). Goals of BioArt could be: Involvement with living matter, exposes hidden emotions and values, demystifies science, public empowerment: enables being otherwise, and/or just focus on methods itself. Artistic skills that are involved are: Irony (Dove d'Or), appropriation (Eduardo Kac, GFP Bunny), rule-breaking (Jennifer Willet, BIOplay), flip-thinking (Chrissy Conant, Chrissy Caviar), identification/objectivication (Tissue Culture & Art project, Victimless Leather: A Prototype of Stitch-less Jacket grown in a Technoscientific 'Body').

At the workshop part, we tried to extract our DNA from saliva using table salt, detergent, lens cleaner liquid, and alcohol. I put the results of my extraction in a small glass bottle. A picture of this is displayed on the top. I am not sure whether this is only DNA, because I might have poured in the alcohol too fast.

Wednesday, April 17, 2019


At 10:48:07, I bought the book Finnegans Wake written by James Joyce in English and published by Penguin Adult in 2000, ISBN:9780141183114, from charity shop Het Goed for € 3.50.


I installed and tried out Meshroom on my set of plant pictures. For open source software, the interface looks good. One of the steps, requires a CUDA (2.0) compliant NVIDIA graphics card. There is a work around, but it results in a lower resolution mess. I have to figure out how the graphics viewer works. I understand they have a plug-in for Maya.

Monday, April 15, 2019


Saturday, April 13, 2019

Tegelreliëf Ad Dekkers

I was invited for the opening of Tegelreliëf Ad Dekkers, a tile relief designed by Ad Dekkers measuring 9 by 18 meters, which was recreated at a park in Bergeijk after it had to be removed from a school in Gouda to make room for buildings. The offical opening was performed by Beatrix of the Netherlands, who knew Ad Dekkers from the meetings she and her husband organized between 1968 and 1975 on Drakensteyn Castle. It is said that she was rather fond of Ad Dekkers. She had one of his sculptures placed in the garden. When they moved to Huis ten Bosch Palace she asked Ad Dekkers for another copy of the sculpture to be placed there. I met with Peter Strucken, who was a good friend of Ad Dekkers. I briefly greated Daniel, the son of Ad Dekkers. I also shaked hands with Rudi Fuchs. I talked a lot with Carel Blotkamp, who also gave one of three introduction talks before the opening of the tile relief. After the official opening, I visited the exhibition about Ad Dekkers. When leaving, I received a goody bag with the books:
  • Louis van Roode: meester in monumentaal maatwerk written by Willem Heijbroek in Dutch and published by De Vrije Uitgevers in 2015, ISBN:9789082453904.
  • Rietveld's design factory re_newed written by Toon Lauwen in English and Dutch, and published by Aerial Media Company B.V. in July 2017, ISBN:9789402602555.

Thursday, April 11, 2019

Be Your Own Robot

I went to the opening of the exhibition Be Your Own Robot by Sander Veenhof. The following are the notes that I took during the artist talk during the opening (with links added later):
    It ia about augmented reality. How does it work in the real world. What is it really about? What do I, as an artist, with it? He started long ago with a Commodore 64. He created Biggâr, the largest virtual art work in the world. In 2010, he made WeARinMoMA. 2011. A virtual traffic light at Oerol. People look a lot at their smart phones. Project Meet your stranger. Now it is called leesluid.nl. Pokémon Go. Google Glass. He (re)created a screen saver for it. Slowly all arguments again augmented reality are disappearing. A virtual glass is looking all the time with you, through the cameras. The idea of virtual fashion. Google now has a patent on making the love gesture for liking something now. He created a patent alert app for augmented reality. The App Store Review Guidelines are quite restrictive. There seems to be not much room for art. All tech companies what you to put on these kind of glasses, because they follow what you see. Companies life Facebook are interested in this information. In the past he often was in Second Life. Now it is almost empty. There you can buy all kind of things to improve your appearance and behaviour. The same thing might happen with AR glasses. He created some apps to make people think about what could happen in the future. The woordenjutten AR app. You could create theather in which people become the actors. With IF _THIS_ THEN I, you can create some rules for yourself. So the answer is: Be Your Own Robot

Tuesday, April 9, 2019


Sunday, April 7, 2019


It was sunny today, with a maximum tenperature of 20.7°C at the official weather station, and the back garden was filled with the smell of our magnolia, which is full of flowers now. Some flowers are already dropping their leaves but there are still some buds that have not opened yet. I am happy that this year I can enjoy the magnolia such a long time. I got the impression that in other years it was over sooner.

Saturday, April 6, 2019


May 2019
April 2019
March 2019
February 2019
January 2019
December 2018
Alzheimer's Disease
Trip to China 2019
-- contact --




Art works
Useless lists


My life as a hacker
Signature programs
Software enginering
The Art of Programming
eXtreme Programming Programs


Hamilton cycles
cutting sticks
Califlower fractal


Volcano Blog


The email address below, may only be used for private communications. This email address may not be put on any mailing list. I do not want to receive emails with advertisements of any kind. My email address is:

Privacy statement

This is a static website with no contact form and no way to add comments. It has no advertisements and no trackers. It does not use cookies. I am not using any method to analyse traffic to this website nor keeping any logs. I am not collecting personal data besides what is published on this website. If you want me to remove any personal data (including your name or link to your website), please contact me by above email address and I will make all effort to remove the data as soon as possible. I am private person and this website does not serve any economic purpose. All cost for maintenance are paid by myself. I do not receive any payments. The website is ad-free and does not have sponsored links.

Site statistics

If I did not count wrong, this site consists of 965 HTML-files with a total size of 22,347,909 characters, having 47,104 internal links and 10,788 external links to (more than) 3,633 websites. (At least 731 of the external links are broken.) Furthermore, it contains 208 C/C++ program files with a total size of 4,702,641 characters, and 3 PASCAL program files with a total size of 35,259 characters. There are 73 text files with a total size of 774,699 characters. With respect to images, this site containts 1245 JPEG images (total size 54,360,652 bytes), 146 GIF images (total size 3,765,046 bytes), 92 PNG images (total size 2,253,317 bytes), and 2 BMP images (total size 3,727 bytes). With respect to sounds, it contains 14 WAV files with a total size of 389,002 bytes and 1 MP3 files with a total size of 70,182 bytes. It also contains 43 PostScript files (total size 308,387 bytes), 2 LaTeX files (total size 132,020 characters), 8 PDF files (total size 640,573 characters), 22 zip files (total size 2,487,335 bytes), 3 gzipped tar files (total size 52,345 bytes), 45 SGF files with a total size of 85,019 bytes, 103 KML files with a total size of 4,332,209 bytes, and 2 EXE files with a total size of 38,340 bytes. It also uses 15 JavaScript files with a total size of 656,113 bytes, This leads to a total size of 100,808,517 bytes.


Creative Commons License

I, Frans hold the copyrights of this and all other pages on this website. For this website a Creative Commons License is applicable. You may not use this work for commercial purposes. I consider all computer programs to be copyrighted by me under the GNU General Public License, unless stated explicitly otherwise. All quotes (text and program fragments) from other sources are excluded from this, and should be considered as copyrighted by their authors.

(This space is intentionially left empty)