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, October 2, 2022

Dier Day Rally

I accompanied Andy on the Dier Day Rally (Animal Day Rally) with Volkswagen Beetle and Citroën 2CV (in the Netherlands nicknamed '(ugly) duck') cars. We were traveling in a 2CV which had been galvanized, the only durable solution to rust. The 2CV is a very minimalistic car, to keep them cheap, but now that they have become rare, the have become worth more.

Saturday, October 1, 2022

Going into the city

Before I went into TETEM where I saw the exhibition Finger Talk by Karl Schulze. In the city, I went to galery Beeld & Aambeeld where I looked at the works by Elsbeth Cochius. I bought a set of ten large postcards with reproductions of her works for € 20.00. At Concordia, I saw a short film I may always ask her anything by Silke Schönfeld. At 15:11:45, I bought Moleskin daily planner for 2023. On the top floor, I saw five prints by Annelies Dam, which are going to be part of the exhibition Hora Ruit, Tempus Fluit.

Thursday, November 29, 2022

Chestnut tree

This afternoon, I cut chestnut tree in the back garden, just like we did in Sunday, March 30. It again was getting rather high with several thick branches that grew from the trunck. Conny helpt with removing the leaves from some of the branches.

Tuesday, September 27, 2022

Arnon Grunberg

I finished reading the book Aan nederlagen geen gebrek: Brieven en documenten 1988-1994 consisting of letters (and some documents) written by Arnon Grunberg, which partly overlaps with the time he wrote his first novel: Blue Mondays (Blauwe maandagen). I started reading this book on September 4. I bought it on May 28. This afternoon, I reread some parts of Blaauwe maandagen and I came to the conclusion that I find it more interesting to read his letters than his stories. Many of his letters are written in the same style as his stories, but where a story is only judged by the readers, the letters are not without consequences with respect to the relationship he has with the people he writes to. That makes them far more real.

Sunday, September 25, 2022


This afternoon, I went to pick up a recent painting from Maaike Goinga. This is the painting, I saw at the exhibition in Robson on Saturday, September 3. Shortly thereafter, I decided to buy it. She showed me her studio and we talked a bit about her recent work.


Thursday, September 22, 2022


Tuesday, September 20, 2022


Monday, September 19, 2022


Sunday, September 18, 2022

12.1° Celsius

Today, the temperature at Twenthe Airport did not go higher than 12.1° Celsius. In De Bilt the highest temperature was 13.3° which made it the coldest September 18 on record, breaking the previous record from 1962.

Saturday, September 17, 2022


Today, I went to Amsterdam by train. I made a stop at Utrecht where I walked to the bookshop Steven Sterk. I saw the book Actie-Reactie: 100 jaar kinetische kunst about an exhibition with the same name (YouTube). I also wanted to visit bookshop Broese, but that have moved to a new location. I Amsterdam, I first went to Architectura & Natura bookshop. I saw the book Tibetan Houses: Vernacular Architecture of the Himalayas and Environs. From there, it was but a short walk to andriesse ~ eyck gallery to see the exhibition Echoes and Traces with works by Lidwien van de Ven. Next I visited Galerie Ron Mandos to see the Best of Graduates 2022 exhibition. I found the works by the following graduates noteworth:

I walked around the area and went to bookshop Boekie Woekie, books by artiss. From there I walked to Athenaeum Boekhandel and, across the street, to The American Book Center. The last bookshop I visited was Scheltema. On the train ride home, I saw some rainbows. First at 18:57 there was a partial (left-side) single rainbow on the left side of the train when we entered the station of the Apeldoorn, which remained visible till about 19:00. Then after we left the station, there was a double rainbow visible on the right side of the train. Because the train was driving away from the sun, I could not see if it was a compelete rainbow, but I suspect it was. It seems that both rainbows were originating from the same cloud. It is typical rainbow weather, just like yesterday, when I too saw a rainbow, with rain clouds that developing when cold air is coming from the north west. I did enjoy this trip to Amsterdam.

Wednesday, September 14, 2022

Book sale

At 17:28, I bought the following three books at the book sale at the book charity shop Het Goed for € 0.99 each:

Solution for #7.410.754

I learned that a decider was implemented that already states that Busy Beaver #43.374.927 does not halt. I decided to work on The Busy Beaver Challenge #43.374.927. I had to make some improvements to the algorithm implemented in SymbolicTM.cpp (see SymbolicTM git repository) to deal with some new cases. I found the following rules that prove this challenge:
A: 0@ 0 .@
E: 0@ 0 0.@
B: 0@1 0 .@
B: 0@1 1 .@
B: 0@ 0 .@
C: 0@((11)+0+)* 0 .@
A: 0@((11)+0+)*(11)+0+ 0 1.@
A: 0@((11)+0+)*(11)+ 0 1.@
B: 0@((11)+0+)*(11)+0+1 1 .@
B: 0@((11)+0+)*(11)+1 1 .@
C: 0@((11)+0+)*(11)+ 0 .@
C: 0@((11)+0+)*(11)+ 1 .@
A: 0@((11)+0+)*(11)*1 1 .@
C: 0@((11)+0+)* 1 .@
D: 0@((11)+0+)*(11)+ 1 .@
E: 0@((11)+0+)*(11)*1 1 .@
D: 0@((11)+0+)* 1 .@
E: 0@((11)+0+)*(11)+0* 0 0.@
B: 0@((11)+0+)*(11)+0+ 0 .@
Note how almost everything on the right tape is irrelevant. Although the behaviour of this Turing Machine looks very chaotic, the left side of the tape is rather regular.

Monday, September 12, 2022


I finished the SymbolicBB.cpp program, which can be used to proof of a Busy Beaver Turing Machine terminate or not. The program (that I talked about last Tuesday) verifies that a collection of patterns, which make use of regular expressions to describe the states of the tape, describe all possible states that can be reached from a starting state. If this does not include a halt state, it proves that the Turing Machine will never terminate. The patterns (as processed by the program) for The Busy Beaver Challenge #43.374.927 that prove that it does not terminate, are:
A: 0@ 0 0@
B: 0@1 0 0@
C: 0@ 1 10@
B: 0@ 0 010@
C: .@ 0 1010@
A: .@ 1 010@
D: .@0 0 10@
E: .@00 1 0@
A: .@001 0 0@
B: .@0011 0 0@
C: .@001 1 10@
B: .@00 1 010@
B: .@0 0 1010@
C: .@ 0 11010@
B: .@ 0 1+(01+)*01+1010@
C: .@ 0 1+(01+)*01+1010@
C: .@ 1 1+(01+)*01+1010@
A: .@ 1 1*(01+)*01+1010@
B: .@ 0 (01+)*01+1010@
D: .@ 1 1*(01+)*01+1010@
D: .@ 0 1+(01+)*01+1010@
E: .@ 1 1*(01+)*01+1010@
A: .@ 0 1+(01+)*01+1010@
B: .@ 1 1*(01+)*01+1010@
D: .@1+ 1 1*010@
D: .@11+ 0 10@
E: .@1+0 1 0@
A: .@1+01 0 0@
B: .@1+011 0 0@
C: .@1+01 1 10@
B: .@1+0 1 010@
B: .@1+ 0 1010@
D: .@ 0 1+1010@
A: .@ 0 1+1010@
E: .@ 1 1+010@
B: .@1 1 1+010@
A: .@ 1 1+010@
D: .@0 1 010@
D: .@1 0 10@
C: .@ 1 11010@
B: .@ 1 1+1010@
B: .@ 0 1+11010@
C: .@ 0 1+11010@
C: .@ 1 1+11010@
D: .@ 1 1+010@
This is a bit more than my earlier proposed solution. It is possible that this collection can still be reduced by making some patterns more generic. I am also thinking about adding some analyses algoritms. For a desciption also see SymbolicTM git repository.



Friday, September 9, 2022


This afternoon, I went to GOGBOT with the title So Future: From Solarpunk to Metaf*ck. I found the following works of the exhibition noteworth: I found that the exhibition was quite interesting. I have to note that some rooms of the exhibition were closed.


At 18:13, we noticed that there was a rainbow on the sky after the sun started to shine while it was still raining. I went outside with an umbrella and took some pictures. I also took a close-up which shows the colour bands below the main colour band.

Thursday, September 8, 2022


Tuesday, September 6, 2022

First chestnuts

This morning, at 9:13, Conny and I found two rather small chestnuts on the Helmerstraat while taking a walk. We think that they are small due to the dry weather of the past months. We had some rain this morning for the first time in many weeks. The tall chestnut tree in the garden is getting too tall and too thick. We are thinking about cutting it down before it getting too tall to cut it down by ourselves. Conny has been taking care of the little chestnut tree after it lost it leaves again early in the summer. It has grown some leaves again and now about 16 cm tall. Kind of bonsai chestnut tree.

Busy Beaver Challenge #43.374.927

I have been working on a program to process the 'rules' I presented last Friday, but it looks like the rules need to be a bit more complicated. However, I cannot exclude the possibility that they need to be far more complicated or that this approach is even not possible. It looks like I also need some more time to develop the program further.



Saturday, September 3, 2022

Going into the city

This afternoon, I went into the city. I first went to the open day exhibition at Robson, Stichting Vierkant. There I saw works by the following artists: I was interested in buying a work from Maaike Goinga and met with her to talk about it.

Next, I went to TETEM art space where I saw the exhibition Morphogenic Angels and Pink Moonrock Cries by Kieken artist collective. I spend some time looking at their presentation in the entrance hall made with Miro brainwriting tool.

At Fotogalerie Objektief I saw the exhibition Ruimte en Perceptie (Space and Perception) with photograpsh by Jan Theun van Rees.

At Concordia there was only an exhibition on the second floor called Groei Festival where Jasper Schütz works together with some people from Enschede to create art. There was an installation activated with a proximity sensor with activated shows you a room full of people applauding.

At bookshop Broekhuis, I saw the exhibition Torino Expo with works by Sander de Groot.

Friday, September 2, 2022


Floor van Lamoen informed me that the center of the triangle that I talked about on August 4 is the orthocenter, which is the point where the three altitudes of the triangle cross. This was already described by Euler as the orthocentric system. Floor van Lamoen is one of the people who have contributed to the Encyclopedia of Triangle Centers. Some information about his contributes are found on his mathematics page (in Dutch).

Busy Beaver Challenge #43.374.927

This evening, I came up with the following 'rules' for the The Busy Beaver Challenge #43.374.927, which if correct prove that it is infinite:

A: .* 0 0*            => B: .*1 0 0*
A: .* 1 010*          => D: .*0 0 10*
A: .* 1 1010*         => D: .*0 1 010*
A: .* 1 1+010*        => D: .*0 1 1*010* 
A: .* 1 (01+)+010*    => D: .*0 0 1+(01+)*010* 
A: .* 1 1(01+)+010*   => D: .*0 1 (01+)*010*
A: .* 1 1+(01+)+010*  => D: .*0 1 1*(01+)*010*

B: .*1 0 0*           => C: .* 1 10*
B: .* 0 (01+)*010*    => C: .* . 1(01)*010*
B: .* 0 1+(01+)*010*  => C: .* . 11+(01)*010*
B: .* 1 (01+)*010*    => B: .* . 1(01)*010*
B: .* 1 1+(01+)*010*  => B: .* . 11+(01)*010*

C: .* 0 1+(01+)*010*  => A: .* 1 1*(01+)*010*
C: .* 1 10*           => B  .* . 010*
C: .* 1 1+(01+)*010*  => B: .* . 01+(01)*010* 

D: .* 0 10*           => E: .*0 1 0*
D. .* 0 1+(01+)+010*  => E. .*0 1 01+(01+)*010*
D: .* 1 010*          => D: .*1 1 0*
D: .* 1 1+(01+)+010*  => D: .*1 1 01+(01+)*010*

E: .* 1 0*            => A: .*1 0 0*
E. .* 1 01+(01+)*010* => A: .*1 0 1+(01+)*010*

Now, I plan on writing a program that can process these rules and proof that the rules are correct and cover all possible cases.


Thursday, September 1, 2022

Drents Museum

Conny and I went to the Drenthe province. We first went to Drents Museum in Assen, the capital of Drenthe. There we saw several exhibitions. The first exhibition we saw was Nebra Sky Disk, which is about the Nebra sky disk. We both had some doubts about some of the texts at the exhibition as they expressed certain interpretations as fact. The object is from a time where there is no written accounts, meaning that there is a lot of room for interpretation.

We revisted the Unlimited exhibtion with self-portraits from the collection of the museum, which we saw on June 16. I found the following self-portraits noteworthy:

We also saw De Drenthe Madonna by Josef Israëls, 1893.

We also revesited the Under the Spell of Mount Ararat exhibition. Again we were impressed by the Armenian alphabet. In the exhibition there was also an Armenian bible printed around 1666 in the Netherlands and being published by Voskan Yerevantsi. Conny bought two books at the museum shop: One about the Nebra sky disk and one about Deborah Poynton.

Decking path

After we visited the museum we went walking in the Dwingelderveld National Park. We walked the 'white' route that contains some decking paths on poles that are in the wet areas. But because of the lack of rain we did not see any water while walking these paths. In the past three summer months there was an average of 135mm of rainfall where 224mm is normal. It was also one of the most sunny summers with 835 hours of sunshine while 640 is the average. It was the third hottest summer after the summer of 2018 and 2003 with an average temperature of 18.6°C against 17.5°C normal.

Wednesday, August 31, 2022


Tuesday, August 30, 2022

Hummingbird hawk-moth

Just before four in the afternoon, there was a Hummingbird hawk-moth in our back garden visiting our butterfly-bush (Buddleja davidii). We had never seen one before. I took three pictures, where the image below is taken from one of them.

Sunday, August 28, 2022

I am Spock

I finished reading the book I am Spock by Leonard Nimoy, which I started reading on July 19 after I bought it on July 9. An interesting book to read, but as some point I felt it was a bit too much an enumeration of trivia facts. I understand that Nimoy choose this title because he received a lot of criticism about the title of his previous book that was called I am not Spock. Everywhere in the book there are fragments of internal dialog between 'Spock' and 'Nimoy'. But having internal dialog with a fictive character does not make yourself that character. I presume that Nimoy, although he strongly identifies with the fictive character Spock, does mean with the title of the book, that he is very much like Spock. Maybe there are people who are more like Spock than Nimoy because I wonder if he has a very Spock like personality seeing what he has achieved as an actor and a director.

Thursday, August 25, 2022

Local heat wave

The temperature at Twenthe Airport has gone up to 32.7° Celsius touches the record of on this date from 2016. It is also the third day the temperatures went above 30°C and because since last Friday the temperature went above 25°C every day, it means we have a local heatwave according to the Dutch rules.


Wednesday, August 24, 2022

32.3° Celsius

The temperature at Twenthe Airport has gone up to 32.3° Celsius, which breaks the previous record of 31.0° on this date in 2016.

Tuesday, August 23, 2022

30.6° Celsius

The temperature at Twenthe Airport has gone up to 30.6° Celsius, which breaks the previous record of 29.3° on this date in 1955.

Irregular grids

I made some implementation for generating irregular grids of squares and equilateral triangles which can be seen below. This is not yet a proof that it it possible to create infinite irregular grids using this method. On April 6, I already showed that there is a method to create infinite irregular grids for each infinte square grid filled with two values.

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

Monday, August 22, 2022


At 17:29:24, I bought the book Bowie's Books: The Hundred Literary Heroes Who Changed His Life written by John O'Connell with illustrations by Luis Paadin, written in English and published by Bloomsbury Publishing in 2021, ISBN:9781526605818, from bookshop Broekhuis for € 9.95. In 2013, David Bowie posted a list of his top 100 favorite reads on his Facebook page. This books is about the 100 books mentioned on this list.

Saturday, August 20, 2022


This afternoon, Conny and I went walking in the hamlet Twekkelo not far from were we live. This is the second time we walked there and just like the first time we parked near the small Johanneskerk (Church of St. John). We followed the green walking route with two small detours. The route consist mostly of walking trails through the fields. Some trails are even along the edge of farming fields. At some parts it looked we were the first to walk the trail for some weeks. I understand that some of the trails were only established in the past three decades. We also came across a stone with the text 'Twekkelo Marke 2018' on it. But because it is in the middle of what used to be the marke it is not a marke stone.

Thursday, August 18, 2022

Unique patterns

Yesterevening when I was brushing my teeth, I got an idea what could be wrong with the algorithm to determine unique regular grids of squares and equilateral triangles. This evening, I implemented a fix in irst.cpp and it seemed to work after I a quick visual inspection of all the patterns.

Wednesday, August 17, 2022


October 2022
September 2022
August 2022
July 2022
June 2022
May 2022
-- 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




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 1025 HTML-files with a total size of 23,853,394 characters, having 51,375 internal links and 13,586 external links to (more than) 4,399 websites. (At least 765 of the external links are broken.) Furthermore, it contains 228 C/C++ program files with a total size of 5,015,004 characters, 10 MySample scripts with a total size of 77,438 characters, 3 PASCAL program files with a total size of 35,259 characters. and 2 Python program files with a total size of 3,764 characters. There are 67 text files with a total size of 739,138 characters. With respect to images, this site containts 1313 JPEG images (total size 58,203,345 bytes), 146 GIF images (total size 3,765,046 bytes), 94 PNG images (total size 2,280,364 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), 11 PDF files (total size 12,472,212 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, 142 KML files with a total size of 5,502,270 bytes, and 2 EXE files with a total size of 38,340 bytes. It also uses 19 JavaScript files with a total size of 1,227,803 bytes, This leads to a total size of 120,115,102 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.