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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.

Saturday, July 4, 2020

TSP solver

In the past week, I tried to find out if there was an even shorter route to complete the AKI MUPI route. I first tried the TSP Solver and Generator. Took me some time to generate a binary .tspt file in the right format. The solver very quickly found a solution of more than 28Km, not even close to the shortest route I had already found. Next, I wrote a recursive back-tracking solver. It worked, but did not make much progress, until I made some modifications that strongly reduced the number of alternatives searched on every level. It did find a shorted route, starting from home and visiting: C, E, I, Q, J, F, G, H, L, K, M, N, O, P, g, a, Z, Y, W, X, l, k, j, i, h, f, e, d, c, b, V, U, T, S, R, B, A, D, and back home where te letters refer to the points on the map, I presented on June 27. Next, I implemented a batch solver, which starts with a batch of 'smallest' possible solutions and extends these in steps. With a batch size set to 5000, this algorithm did not find any shorter algorithms. I added some of the output to the source of the program.

Sunday, June 28, 2020

AKI Mupi route

Today, I biked the route (in Google Maps) I found yesterday, although I followed the route by heart (except for some small change), I missed one of the Mupi's along the route. It was the Mupi with a reproduction of the works by Julia Hofman. I left at 9:29 and returned at 12;03. Below the list of Mupi's I encountered with a short description of the work as I precieved it.

Saturday, June 27, 2020

Planning AKI Mupi route

I wanted to find a route to visit all the Mupi's of AKI Finals Mupi route. I spend some hours drawing connection routes (with Google Earth) between the mupi locations and noting down the distances. (The results in KML file or Google Maps.) I made a drawing of this:

Finding a shortest route is the Traveling Salesman Problem as a graph. I searched for a solver. I came across TSLIB95. I installed TSPLIB 95, but when I enter the import tsplib95 in Python 2.7.17, I get a SyntaxError on line 5 of bisep.py. The pages do not mention which version of Python should be used. I downloaded tsp_brute from Brute Force Solution of Traveling Salesman Problem and got it compiling with g++ with some modifications. Next I wrote a program to generate the matrix from the graph. The tsp_brute took a long time crunching and I killed it after some time without it producing a solution or showing any sign of process. I tried to find some route myself, and fount a route of length 26.181 meter. Next, I wrote added an algoritm that incrementally removes the longest connection lest any node get less than two connection. From the resulting list of fragments, soms cicular, some with branches, I constructed another route with a length of 25.641 meter.

Thursday, June 25, 2020


Tuesday, June 23. 2020


Monday, June 22. 2020


Sunday, June 21, 2020

Father day present

Annabel gave me a pyramid maze, which she has made from wood with a laser cutter and for which I wrote the program. Below a photograph of the maze.

Friday, June 19. 2020


Wednesday, June 17, 2020

Suguru puzzles

I wrote a program to map Suguru/Tectonic puzzles on an Exact Cover. The exact cover solver should be able to read the input of a number of columns separated with commas, where the numbers may be in any order. The program reads the input from the standard input. An example of the input format is:

| |4  |4  |
*-* * * * *
| |  1|  2|
* *-* * *-*
|   | | | |

Monday, June 15, 2020

Red rainbow

When at 21:56 I left home the sky was red due to the sunset. It was also raining a little and I saw a faint single but complete rainbow. I also noticed that it was quite red. Just before ten, I took a picture, which is show here, after I increased the saturation a little to increase the visibility of the the rainbow.

Wednesday, June 6, 2020


Monday, June 6, 2020


Saturday, June 6, 2020


Thursday, June 4, 2020


At 17:17, I bought the following books from charity shop Het Goed:
  • De Eersten van Rissan written by Wim Gijsen in Dutch and published by Meulenhoff in 1984, ISBN:9029011432, for € 1.65.
  • Bovengronds: 15 jaar kunstbezit bij Gasunie edited by Chris de Boer and Jan Hekman, written in Dutch, and published by N.V. Nederlandse Gasunie in November 1997, ISBN:9789071728150, for € 1.45.
  • One hundred thirty seven thousand and sixty-one edited by Dorrie Tattersall and Petra van der Jeught, written in English and published by Jan van Eyck Academie in 2009, ISBN:9789072076885, for € 3.00.

Monday, June 1, 2020

Sunniest spring

The past three months, where the most sunniest on record. On average over the whole country we had 790 hours of sunshine while on average there are 517 hours. The previous record from 2011 was 743 hours. It was also very dry. We only had (on average over the whole country) 77mm where 172mm is normal. The weather station at Twenthe Airport measured 752.2 hours of sunshine and 95.5mm of rainfall.

Sunday, May 31, 2020


Conny and I went on another hunt for border poles. This time our goal was the Drilandstein, a border pole on the border of The Netherlands and the German states North Rhine-Westphalia and Lower Saxony.

The poles we encountered are:

Some links (in Dutch) with information about poles along the route that we took:

Tuesday, May 26, 2020

Noise Engine 1

In the evening, I went to TkkrLab, where there were but a few people. I bought a breadboard from the vending machine and went to experiment with the 40106 IC from the 4000-series integrated circuits, which has six inverting Schmitt triggers. I used three of these to make a circuit. For a short demo, see the Noise Engine 1 YouTube video.

Monday, May 25, 2020


This afternoon, I discovered that the little cestnut tree has withered. I must admit that I have not watered the flower pot is planted in and that it must not have had enough water due to the extreme dry and sunny weather of the past weeks. I will try to remember to water it in the coming weeks.

Friday, May 22, 2020

Resistance against measures

The resistance against the COVID-19 measures is increasing in particular agains the 1.5 meter distance rule. Yesterday, the weather during Ascension day was quite nice, so many parks, beaches and recreation areas were crowded and many people ignored the distancing rules. Some people from the catering industry have started a facebook group agains the measures, which are difficult to apply when they are allowed to open on the first of June. There is also criticism from scientists, like a Ira Helsloot, professor of Safety Management at Radboud University, who states (Google translate translation from Dutch): "If you look back in the statistics, we know that the 'intelligent lockdown' would not have been necessary."and continues to explain that all other measures, like staying home when having a cold, had the greatest effect. There are also people pointing at the evidence for aerosol transmission of COVID-19, especially in crowded, noisy indoor locations, where people are talking loud and/or singing. If transmation does not happen through aerosols, as the RIVM is claiming, there is no need to keep the 1.5 meter distance when people are not coughing and/or sneezing. There are also people who have a problem with the fact that the government (and the RIVM) are still aiming for herd immunity and not aiming at containment. In the worst infected region, around 10% of the population has been infected. In other areas, like ours, it is around 3%, but in most areas it is even lower. And even in our area the percentage is probably so high due to a number of localized outbreaks. The RIVM is stating that a vacin may not be effective and that herd immunity is the only possibility. But at the current rate it is going to take years before the required infection rate is achieved, and it is still an open question whether someone who has been infected, will remain immune for many years or that the virus will mutate, because corona viruses are known to cause repeated infections in people throughout their lives. See also this interesting timeline with respect to COVID-19 in The Netherlands.

Thursday, May 21, 2020

Dew walking

Conny and I followed the old tradition of 'dew walking' ('dauwtrappen' in Dutch), which involves going on a bike trip early in the morning of Ascension Day. We left at about a quarter past five. When we came outside of the city, we noticed mist over a lot of fields and also over the lake at Ruthbeek. We planned to scout for border poles along the border with Germany. Yesterday evening, I had compiled a route. This are the border poles that we found:
  • At 6:12, pole 840.
  • At 6:17. pole 839-B.
  • At 6:23, pole 840-B, also known as "pfeal an der Mesemate".
  • At 6:28, pole 840-D. (This pole is not mentioned on the map of the markegrenzen.nl website.)
  • At 6:32, the Wertherpaal.
  • At 6:48, the poles 840-H and 804-G. Along the road to these poles, there are some building belonging to the railway station Broekheurne, which was in operation between April 25, 1903 and April 29, 1967. It appeared that the road called Zuidergrensweg was private property, meaning that we could not go there and had to skip some part of the planned route.)
  • At 7:13, the poles 843, 842-L, and 842-K from a distance while standing on the road called Berenbroeksweg.
  • At 7:16, pole 843-C. (Not in my planning.)
  • At 7:20, pole 843-D. (Not in my planning.)
  • At 7:25, pole 844-A. (We missed pole 844, while we walked past it.)
  • At 7:33, the two border poles from unknown origin that recovered as being used for a fundation of a building and placed in a field along the road called Aamsveenweg. (Not in my planning.)
  • At 8:17, pole 845-C.
  • At 8:32, pole 845-E from a distance because it being in a raised bog. (We did not see pole 845-D, which must be behind it from the point we saw it.)
  • At 8:34, pole 845-G.
  • At 9:29, pole 845-M. (This and the following two poles where not along a route in my planning but found when taking a detour.)
  • At 9:33, pole 845-K.
  • At 9:37, pole 845-H. Conny walked to 845-G again. (At home, I discovered, we missed poles 845-J and 845-L.)
  • At 10:12, pole 847.
  • At 10:22, two poles 848, a Dutch one and a German one, which are both sides of the brook called Glanerbeek where the border is in the middle of the brook.
From there we biked home.


Wednesday, May 20, 2020


Friday, May 15, 2020

-1.8° Celsius

Last night, between 5 and 6, the temperature at Airport Twenthe at 1.5 meter height dropped to -1.8° Celsius, while at 10 cm the temperature dropped to -6.9° Celsius. This broke the record of -1.2° of 1973. This type of low temperatures, do happen more often during this period of the year, and a lot of records have been broken in the past twenty years, which seems a little counter intuitive. One reason that the temperature dropped so low, is that the air is relatively dry. This causes clouds to disappear during the night and air to cool faster. We get this dry air because of winds from the North and the East. It has been this type of weather sinds the start of April with only a little rain, less than the driest year, 1976, on record. It is caused by high pressure systems North passing over Scandinavia.

Thursday, May 14, 2020

Superclean Dreammachine

I found a website of the radio program Superclean Dreammachine. This program was made and presented by Ad Visser and ran from May 15, 1968 to September 29, 1980. (He also presented the TV show TopPop.) I often listened to the radio program because it had a mix of alternative music styles often with synthesizers. I even remember having listened to some dummy head recordings supposively made in Egypt, but I am not totally sure it was part of this program. Several times, I recorded the program on a cassete tape. I did this on May 29, 1978. The recording referred to on the website is this recording. The show started (some songs from) with the album Shpritsz. The next part was announced with: "The legends of King Arthur and the Knights of the Round Table. Luister naar de muziek van ex-jazz musicant Rick Wakeman. Sinds kort weer terug samen met The Royal Philharmonic Orchestra." I liked it very much and listened to it many times. I still have the tape somewhere in the attic. I tried to find the recording and I even ordered The Myths and Legends of King Arthur and the Knights of the Round Table only to discover that this was not the recording I was seeking after. Tonight, I discovered that it was actual the LP The Royal Philharmonic Orchestra plays Rick Wakema that was play. I am happy that I have found this recording after so many years.

Monday, May 11, 2020


Sunday, May 10, 2020


This morning, Conny and I went biking and walking around the Zonnebeek estate. We walker around the forest for almost an hour. There were quite a lot of mosquitos. Half way we had a look at the american style country house, which was build around 1907 by (Jan) Bernard van Heek and Edwina Burr Ewing, who came from Nashville, Tennessee. They donated a large part of their art collection to Rijksmuseum Twenthe. They also donated the Buursezand, a large nature area, to Vereniging Natuurmonumenten. We continued biking a came along another marke stone, the Leppepaal or Leppinkpaal, which is in the middle of a field. It is standing at the border of the marke Usselo and Buurse. We continued biking and crossed the Buursezand.

Friday, May 8, 2020


Thursday, May 7, 2020

Test and track

Yesterday evening, our government presented the provisional road map for ending the lock-down measurements. During the press conference, the government said they would focus on testing and tracking. The plan is that from June 1, tests will be made available to everyone, not just restricted to certain professions, as it has been up to now. The number of positive cases are slowly dropping, so it would be no problem. There will also be an experiment with opening some care homes. As far as I know, the one that Andy lives at, is not included. No mention was made about mental health care, which some people are dissapointed about, because hairdresser are allowed to open again. In the past months, our government has been stating over and over again, that face mask are not useful, but now they are stating that non-medical grade face mask should be worn when making use of public transportation. The motivation for this is that the 1.5 meter distancing is not possible in public transportation. (There is still a shortage of medical grade face mask.) There is no evidence that the 1.5 meter distancing rule has been the most effective measurement with respect to stopping the spread of the SARS-Cov-19 virus, but it seems it has been declared to the holy rule that everyone should stick to, while experts recently announced that people still having trouble with proper hand washing procedures.

Tuesday, May 5, 2020

"Digital" mirror date

Today is a "Digital" mirror date, the first for the date formats MM/DD/YYYY and YYYY.MM.DD, and the second for the format DD-MM-YYYY. This is the fifth special date of this year.

Herd immunity

Today, the news came that Sanquin, the Dutch organization for blood and blood product, announced that they have ordered a milion tests for the SARS-CoV-19 virus in the research about immunity for the virus. They want to use this tests in their ongoing research about herd immunity, but also for the extraction of antibodies that could protect vunerable people agains becoming infected. Some weeks ago, the already concluded that about 3% of the population had been infected. With the current number of new infection, I cannot believe this percentage has reached 10% by now. This while for herd immunity you need somewhere between 29% and 74% infection rate based on the estimated of the infection rate. It is difficult to estimated the actual infection rate, because all the lock-down measurements make it substantially lower. Without these measurements, you might need more than 50% infection rate for herd immunity. To me, this research in herd immunity seems rather useless. Would it not be much beter to use the test all the people who think that they were infected and do some reseach into what are the major risc factors for getting infected and what are the most effective counter measurements to be taken to avoid another outbreak? I heard some story about someone who got infected on a skiing trip, but did not infect his family members while being in quarantine when he was ill. It seems that Iceland has succeeded in eradicating COVID-19 by extensive testing and tracking. It seems that the Dutch public health services do not know if they are ready to test teachers now that primary education is going to be reopened next week and that they are not able to actively track cases that test positive. It sounds like bureacrating problems are preventing them from doing this.

Sunday, May 3, 2020

Border and marke stones

Conny and I went on a biking and walking trip again. We first visited the Groot Brunink estate again. We found a small path throught the fields that Conny did not know yet. After we had walked around for about an hour, not counting the short break we took (during which Conny took a picture of me), we continued on bike. We first biked to the border with Germany. There we found the marke stone, named Werthepaal, which is at the cross point of four markes, three in the Netherlands: Esmarke, Usselo, and Buurse, and one in Germany: Alstätte. This stone also marks the border with Germany. It was placed there in 1743 but in the seventies it was lost for some time and when found again, placed on a new foundation at the original location. We continued along the border to the South. We found another border stone, with the offical number 840-B, called: "pfael an der Mesemate". We biked through 'Witte Veen', where it was quite busy, and Conny lead me to another marke stone named Veenpaal. This one looked quite new, and indeed, it was not an original stone, but a replica, placed there in 2013 and officially revealed on November 14, 2015. At home we took some time to do some research about border stones.

Saturday, May 2, 2020


I got the following two books:
  • De sprong der paarden en de zoete zee written by Harry Mulisch in Dutch and published by J.M. Meulenhoff in 1964.
  • Tao te ching: de kunst van harmonie written by 老子 in Dutch published by Librero in 2009, translated by Wilma Paalman from the English The Art of Harmony, which was translated from the Chinees 道德经, ISBN:9789057645310.

Friday, May 1, 2020


Wednesday, April 29, 2020

Small chestnut tree

Yesterday afternoon, Annabel noted that the small chestnut tree, that I feared had died, was growing again. It has some bright leaves. The stem seems thicker and has a strange twist a few centimeters above the ground. This is an interesting development. This afternoon, I took a picture, which is displayed on the right.


Monday, April 27, 2020


July 2020
June 2020
May 2020
April 2020
March 2020
February 2020
Alzheimer's Disease
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