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Dutch / Nederlands

Diary, August 2020

Sun Mon Tue Wed Thu Fri Sat
  2   3   4   5   6   7   8
  9  10  11  12  13  14  15
 16  17  18  19  20  21  22
 23  24  25  26  27  28  29
 30  31

Sunday, August 2, 2020

Round Goki puzzle

I have written a program to analyze the round Goki puzzle that I bought last Wednesday. The program can be used to generate an Exact Cover, to compress the resulting solutions and has some options to analyze the results. There are but a limited number of ways the pieces around the central round piece can be placed not taking into account rotations and mirroring. If we furthermore ignore the colouring of the pieces, but only look to the layout, there are 1,789,051 unique solutions. This is much more than I had expected when I bought the puzzle. To structure the solutions, one can look at the number of possible outer contours when adding pieces from the center. I have sorted the pieces from the center to the outside, first by the first circular layer they occur in, next on the number of circular layers they cover, and next on the number of radial sectors they cover. Below the list of number of countours by selected number of pieces (where all pieces with the same shape but a different colour are counted as one): 1, 2, 5, 5, 28, 13, 13, 26, 12, 30, 55, 55, 588, 1202, 402, 236, 20, 4, 1, and 1 (obviously). I also looked at the correlation between the positions of inner and outer pieces with respect their occurences in the solutions, and it seems there are no strong correlations.

Monday, August 3, 2020

Marke stones

Conny and I made a biking trip of about 32Km along some marke stones on the South and West borders of the Enschede township. These are the marke stones/poles we visited: We searched for the Fabelhuttesteen, but did not find it, not knowing the exact location. At home we discovered that we must af approached it within less than 10 meters.

Tuesday, August 4, 2020


I paid a visit to TkkrLab for the first time in a long time. There were about nine people present. We did have a metameet. I spend some time programming. I also reorganized my box at the space. I had forgotten it contained the motherboard of my first PC. I donated three SCSI harddisk of 36Gbyte to another member, who wanted to something with harddisk platters.

Wednesday, August 5, 2020

Round Goki Puzzle (2)

I continued working on the program for the Round Goki puzzle. I did some refactoring and introduced an iterator, with some goto statements, which looks rather strange until you understand how it works. It implements a recursive function where an array is used to store the variables on the stack. The label l_call indicates the starting point of a (recursive) call and the label l_return gives the location where the call should return. I added some functions to calculate for each combinations of two (type of) pieces the possible combinations do occur in a solution. Below a table is given of the percentages of combinations that do not occur in a solution, where zero is replaced by a dash for clarity. A dash thus means that one can place the two (type of) pieces freely on their possible locations (not overlapping each other) and always can find a solution to the puzzle. The colomn marked with a hash, gives the number of ways to place the (type of) piece, which is higher if there is more than one piece of given type.

    #   A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R
A   2
B  12   -
C  66   - 95
D  54  88 56 91
E  12  75  - 78 67
F  12  59  - 75 75 13
G  12  13  - 64 39  -  -
H  12  21  - 63 47  -  -  -
I  12   -  - 64 30  -  -  -  -
J  12   -  - 64 30  -  -  -  -  -
K  12   -  - 64 30  -  -  -  -  -  -
L  54   - 12 79 43  6  3  -  1  -  -  -
M 220   - 28 84 54 17 12  4  7  - 22  -  1
N  66   - 16 78 44 10  7  2  3  -  -  -  - 17
O  12   -  - 64 23  -  -  -  -  -  -  - 52  4  -
P 220  24 48 89 66 38 38 31 36 85 29 30 92 44 44 42
Q  12   -  - 64 23  -  -  -  -  9  -  -  - 34  -  - 30
R  12   -  - 64 23  -  -  -  -  -  -  -  - 10  -  - 42  -
S  12   -  - 64 23  -  -  -  -  -  -  -  6 24  -  - 22  -  -

Friday, August 7, 2020

Ammerter Gräberfeld

Conny and I made a trip to the Ammerter Gräberfeld nature reserve in Germany in the hope to find some more information about the archaeological findings in the area. The area is along the Flamingo biking route which is on both sides of the border between the Netherlands and Germany. We had seen it on one of the maps along the route. We walked along the biking route along the area but did not find any information signs.

Sunday, August 9, 2020

32.2° Celsius

The temperature at Twenthe Airport went up to 32.2° Celsius, which breaks the previous record of 31.7° for the temperature on this date in 1992.

Monday, August 10, 2020

32.9° Celsius

The temperature at Twenthe Airport went up to 32.9° Celsius, which breaks the previous record of 32.5° for the temperature on this date in 1975.

Tuesday, August 11, 2020

34.6° Celsius

The temperature at Twenthe Airport went up to 34.6° Celsius, which breaks the previous record of 34.3° for the temperature on this date in 2003.

Thursday, August 13, 2020


At 09:25, I bought the following two book from charity shop Het Goed:

Eight tropical days

We had a record of eight tropical days in a row, where a tropical day is defined as a day with temperatures above 30° Celsius. This broke the previous record of six days. The minimum and maximum temperatures of the past days at Twenthe Airport weather station are:

           min.  max.
August  6  14.1  31.7
August  7  14.4  34.2
August  8  14.4  34.6
August  9  18.5  32.2
August 10  15.3  32.9
August 11  19.7  34.6
August 12  18.7  33.3
August 13  18.6  32.0

Around 20:15 it started to rain with some thunder and lightning. The prediction for maximum temperature is 26.8° Celsius and stay around that level for the coming days.

Saturday, August 15, 2020

One / Een

I went to Concordia to see the exhibitions. I did not have to register on forehand like a few months ago. I saw the exhition One / Een with works from twelve artist from the region. I took one of the information leaflets and did not immediately realize that it was the Tweants dialect version. Due to the heat and the high humidity, I could not really concentrate and I only very causally walked through the exhibition. I liked the works by:

Monday, August 17, 2020

Heat wave

The heat wave (according to the definition used in the Netherlands) that started on August 5 has ended today, with yesterday being the ninth tropical day with temperatures above 30° Celsius. Last Friday the temperature reached 29.9° Celsius at the weather station at (the former) Airport Twenthe.

Tuesday, August 18, 2020

Anet A6 Prusa i3

This evening, I got an Anet A6 Prusa i3 3D printer from a member of TkkrLab. I want to see if I can get it running with some slicer software and also think about writing programs that generate G-code for it. I found the specification of the Prusa-specific G-codes.

Sunday, August 23, 2020

Museum MORE

Peter Struycken invited Conny and I for a visit to Museum MORE. I had never heard of this museum before. There were three exhibitions. The first exhibition was a selection of works from the collection of the museum. I found the followings works notable:

Next we saw the exhibition of Jan Mankes. I found the following works notable:

Finally, we saw the exhibition Jan Beutener | After All. I found the following works notable:

Wednesday, August 26, 2020


Zomergasten ("Summer Residents") is a program on Dutch television which takes up an entire Sunday evening, lasting typically three hours, in which a notable guest is being interviewed interspersed with (usually ten) cinema or television footage selected by the guest. Earlier this summer, Conny asked what would be my ten selections for fragments that I would use if I would have been asked to appear in the program. Here is my list of ten (actually eleven) fragments:

  1. Final dialog between Spock and Kirk of The Galileo Seven.
  2. Fragment from Dune: Crisis and observation.
  3. Fragment from The Imitation Game (Turing) Alan Turing and detective Robert conversation - The Imitation Game
  4. Does John Conway hate his Game of Life?
  5. Life, Death and the Monster (John Conway) - Numberphile (About the Monster Group)
  6. Hollandse Meesters: Peter Struycken
  7. Sean Carroll - "From Particles to People"
  8. Proof: "I wrote it" scene
  9. Oona...
  10. Esmerine "Spiegel im Spiegel" (Arvo Pärt) - - For Lhasa's Birthday

The guest can also select a movie, which will be broadcast after the program. My choice would be the movie Proof.

Saturday, August 29, 2020


At 14:12, I bought the book AKI eindexamen catalogus 2001: wat is de filosofie achter je werk? written by Boris Veldhuijzen van Zanten, Nelleke Zandwijk, Sipke Huisman, and Maarten Binnendijk in Dutch and English and published by AKI in 2001, ISBN:9789075522181, from Kringloop Enschede for € 1.00.

Sunday, August 30, 2020

PARR generator

I have implemented an algorithm using JavaScript to generate a random PARR configuration, which consists of a number of dots on a four by five grid connected with a number of lines. The number of dots and lines can be specified. For pratical reasons the number of dots is limited to a maximum eleven. I took care that every possible configuration has the same change of being shown. This algorithm generates all possible configurations without any restrictions, which means with crossing diagonals and not all dots connected.

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Dots: Lines:

This months interesting links

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