## I write, therefore I amWith 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. | ||||||||||||||||

## Monday, May 21, 2018## KunstenLandschap 2018In the afternoon, I went to KunstenLandschap 2018 (Art and landscape), which is a route along
19 (or so) locations, where some art is on display. I followed the route from
the first to the last location. Then I went back to one of the fighter bunker
to watch a dance performance by Tess
Lucassen and some others. There was also a puzzle quest. There were five
locations where you could make yourself woodcut print in the form of a puzzle
piece, that when put together formed one artwork of 40 by 60 cm designed by
Elsbeth Cochius. I made a KML file for Google Earth of the route that I biked. I met several people that I knew.
One of them was Kira Fröse, who had
decorated the inside of a small shelter bunker (at location Number 11). I
liked the following works the most:
*Lost & Found Orchestra*sound installation in one of the figher bunkers by Daniel Maalman.*fotonenstroom / flood of photons*by Nikki van Es.- Five whale fins in pond by Yuri van Zeijl.
- Sculpture
*Duir*by Klaas Kamphuis. - Paintings by Anneke Hansum.
- Ole Nieling with his performance installation KINGDOM, which is especially nice for children.
## Sunday, May 20, 2018## Three fold rotation symmetryI thought about a way to visualize the long sequence of coloured rubber straps, and I came up with the following figure:
In this figure there are ten triangles, one for each combination of the five coloured rubber strapts, such that the vertices are on a circle representing the repeated sequence. There are fifteen pairs of parallel lines, where each pair represent two combination occuring in both directions along the sequence. At first sight the figure seems to have some mirror symmetries, but actual it has a three fold rotation symmetry. ## Saturday, May 19, 2018## Daries of Doeschka MeijsingI finished reading the bookEn liefde in mindere
mate: dagboeken 1961-1987 about the diaries of Doeschka Meijsing, a Dutch novelist. This is part one, as she died in
2012. It seems that the second part has not been published yet. Almost half of
the book consists of notes. Some of the notes, contain back ground information
that is not really relevant for understanding the diary. The editors of the
diaries, made a selection of her diary. They did not give information about
the ratio of entries they selected. I felt they might have better included more
entries and make the notes more concise. It was an interested read. It does
show, as so many biographies before, that people wrestle for many years with
problems in their lives and have a very hard time to change there basic habits.
## Thursday, May 17, 2018## Link## Wednesday, May 16, 2018## Links## Tuesday, May 15, 2018## Link## Wednesday, May 9, 2018## BookAt 9:52, I bought the following two books from charity shop Het Goed:*The Awakening and Selected Short Fiction*by Kate Chopin, Rachel Adams, and George Stade (also editor) in English and published by Barnes & Noble in 2005, ISBN:9781593081133for € 1.50.*The Awakening - Thrift Study Edition*written by Kate Chopin in English and published by Courier Corporation in 2010, ISBN:9780486475660, for € 0.95.
*Ravian: Het woedende water*translated from*La Cité des eaux mouvantes*, ISBN:9032003217, for € 2.50.*Ravian: Land zonder sterren*translated from*Le Pays sans étoile*, for € 1.95.*Ravian: Het verloren volk*translated from*Bienvenue sur Alflolol*, ISBN:9032003217, for € 1.95.*Ravian: De ambassadeur de schaduwen*translated from*L'Ambassadeur des Ombres*, ISBN:9032002368, for € 1.95.*Ravian: De vale schepper*translated from*L'Sur les terres truquées*, ISBN:9032002376, for € 2.50.*Ravian: Brooklyn station eindpunt cosmos*translated from*Brooklyn station terminus cosmos*, for € 1.95.*Ravian: De levende wapens*translated from*L'Sur les terres truquées*, ISBN:9067933147, for € 1.95.
## Monday, May 7, 2018## DroomkoppelThis afternoon, I bought a print of the woodcut 'Droomkoppel' from Willemijn Calis, which I saw on April 14 at the exhibition 'China Dreams'.## Sunday, May 6, 2018## Link## Saturday, May 5, 2018## Links- EEVblog #1081 – Are Bypass Capacitors REALLY needed?
- Synthetic consciousness: the distributed adaptive control perspective
## Friday, May 4, 2018## Link## Thursday, May 3, 2018## Three Dune BooksAt 09:49, I bought the following three book from charity shop Het Goed, for € 0.95 each, all written in English and published by New English Library:*Dune Messiah*written by Frank Herbert, published in 1977, ISBN:9780450032660.*Children of Dune*written by Frank Herbert, published in 1977.*God Emperor of Dune*written by Frank Herbert, published in 1981, ISBN:9780450052620,
I have now all books of the Dune series written by Frank Herbert both in English as in Dutch. I have not read all of them in both languages. ## Tuesday, May 1, 2018## 428,362 sets of equationsI calculated that there are 428,362 sets of equations for the the Irregular Chocolate Bar problem for the problem of finding 22 unique integers which can be divided in up to and including 10 partitions. (This calculation took 13 hours 39 minutes.) So far, my program has searched 62,378 of these sets of equations and found 959 solution with some duplicates resulting in 554 unique solutions. It looks like the program will require some more months to search the remaining sets of equations.## Monday, April 30, 2018## BookAt 09:31, I bought the bookSur Place, Catalogus / Catalogue edited by
Maria Anne van Dijk, written in Dutch and English, and published by Fortis
Stichting Kunst en Historisch Bezit in 2007,
ISBN:9789090216461, from charity shop Het Goed
for € 3.50.
## Link## Sunday, April 22, 2018## Peterson graphI thought about making a pendant of the Perterson graph. I had something like the Petersen Graph Pendant in mind, and I thought about making it from a copper wire. Then I wondered if it would be possible to make it out of a single copper wire, where each edge is visited twice in opposite direction. At home I adapted the program I wrote two days ago, because trying this by hand seemed too complicated, and it found 960 'different' solutions of 30 combinations where the minimal distance between two occurences is five. No solutions with a greater minimal distance were found by the program. Five is two less than seven as found with the solution with 20 combinations. I also discovered that 720 of these solutions have five combinations occuring just five positions from each other, and 240 solutions with only three combinations occuring just five positions from each other. There was no further subdivision with respect to the occuring distances between combinations. It would not surprise me if there are basically only a few (two or four) solutions. I have not yet decided whether I am going to switch to the sequence of 30 combinations. Luckily, I can delay the decision till the thirtieth of the month because I found a solution that is similar until that day. The combinations for that sequence are displayed below:## Saturday, April 21, 2018## Link## Friday, April 20, 2018## Coloured rubber strapsAbout two weeks, I bought a ball of coloured rubber straps, with the intent to use as hair rubber straps. I got the idea to use two straps with different colours every day from a set of five colours. I also do not want to wear the same colour on two consecutive days. I reasoned that there must be a sequence of ten combinations that I could follow (because there are ten combinations of five colours). When I wrote a program to count all the solutions, I discovered that there was none. Next, I searched for a solution of twenty combinations where each combination is included twice, and I found many. In search of an elegant solution, I wanted to avoid solutions where some colour is not used for some time or used on a long sequence of alternating days. Then I realized that I also did not want to wear a certain combination on days that are close together. However, in each solution of twenty combinations, there was a combination that appeared only three days apart. While thinking about this, I realized that the combinations are like the vertices in the Perterson graph. This also explains why there was no solution for ten combinations, because the Peterson graph has no Hamiltonian cycle. I wondered whether anybody ever studied the existence of paths that visit each vertex exactly n-times, a generalisation of Hamiltonian cycles (for which n equals 1). Maybe one reasons is that many graphs that do not have a Hamiltonian cycle do have a cycle which visits each vertex twice, and/or that there exists a rather simple constraint for which a graph contains a cycle that exactly visits each vertex n times. But adding the requirement that each there must be at least k vertices between two consecutive visits, may make it interesting. One could even state that fraction k+1 divided by the number of vertices defines the Hamiltonianess.When I tried to find an elegant solution on paper, I realized that there was an error in the part of the algorithm that calculated the distance between reoccurences of the same combination of coloured straps. When I corrected the algorithm, it counted 60 solutions with at least seven other combinations between each combination. The solution I had found on paper, was on of the 60 solutions found by the program. I strongly suspect that all solutions are basically the same, with the colours and the starting position permutated, because there are 10 combinations and 3! ways in arranging the neighbours of a certain combination. I wrote a small fragment of JavaScript to calculate, which combination to wear on the coming ten days (from today). (I am not going to publish the program, because it seems I could have figured out everything on paper.) ## Link## Thursday, April 19, 2018## AKI takes overIn the afternoon, I went to see the exhibitionAKI takes over: "Hotel Bella Arte" at the University of Twente with
works by Nils Leibeling and Jelle van Assem.
## Almost 30°At two meter, the maximum temperature at weather station at Twente Airport was 28.7° Celcius and at 10 cm it was 29.9°. It would not surprise me if these are record high temperatures for this day of the year. Most flowers of our magnolia have fallen off. A tulip has opened in the back garden.## Wednesday, April 18, 2018## Link## Tuesday, April 17, 2018## BooksAt 16:32:40, I bought the following two books from charity shop Het Goed:*Deeltijdopleiding Fine Art Enschede 2011*written in Dutch for € 0.95.*Welchen soll ich nehmen?*written by Eva Heller in German and published by Ullstein in 2003, ISBN:9783550084157, for € 1.95.
## Saturday, April 14, 2018## China DreamsI saw the exhibitionChina Dreams by Willemijn Calis at XPO. The works on display were made during her trip
to Dalin, China. I found one of the works quite interesting and contacted her.
## Friday, April 13, 2018## Easter Egg in the GigatronWhile showing the Gigatron TTL microcomputer to some family members, I hit upon an animation that I had not seen before and that to my knowledge has not been published. I conclude that this must be Easter Egg build into the ROM by Marcel and Walter. I have not yet discovered the exact steps to activate the Easter Egg, but I was able to activate it a second time. I found nothing in the gigatron-rom at GitHub related to the Easter Egg, which seems to imply that the ROM is either different version than the one published there (or that the target files published there are different that the ones produced by the sources). Have fun with you Easter Egg hunt!
## Tuesday, April 10, 2018## Cosey Fanny TuttiThis morning, I finished reading the auto-biographyCosey Fanny Tutti (by herself), which I started reading on March 19, the day after I
bought the book. It was an interesting read. A red
thread in the book is her complicated relationship with Genesis P-Orridge, who is called Gen in the book.
## No solutions for 10 with 21 integersSome days ago, I started the new program for the the Irregular Chocolate Bar problem for finding solutions for 10. Today, I saw that it found solutions with 22 integers. Not surprising, because last September, I already found 885 such solutions. It seems that there are no solutions with 21 integers, as the program started searching from 20 integers. One of the solutions (with 22 integers) that the program found, is: 10, 28, 33, 38, 45, 52, 53, 73, 80, 81, 102, 108, 115, 137, 143, 150, 172, 199, 200, 207, 242, and 252. This solution is not included in the 885 solutions that were found last year. I am not really surprised about this and expect that the progam will find many more such solutions.## Sunday, April 8, 2018## MagnoliaThe first flowers of our magnolia have opened today. Yesterday, they almost opened. This weekend it is the first time this year we have temperatures above 20°C. In March we had some very cold periods and I hope they will not happen again.## Gigatron: reading data from ROMThe Gigatron TTL micro-computer has a Harvard architecture, which means that instructions and data are not accessed in the same ways as in the now commonly used Von Neumann architecture. The Gigatron has no instruction for reading data from the ROM, which only contains instructions (and their operands). This evening, I discovered that there is a very clever trick by which it is possible to read data from ROM by clever use of the two step instruction pipe-line and the fact that the pipe-line is not cleared during a jump/branch. This means that the Gigatron will always execute the instruction following the jump expression. The trick is to use a jump instruction to a location in the ROM where there is a load immeditate instruction (loading the data in the accumulator) and let this follow by another jump instruction to (for example) the next memory location. This causes the load immediate instruction to be executed when the program counter has returned to the next memory location. See the following table for a step-by-step flow of events, where the 'normal' flow of execution starts at 0x0804 and the data is stored at 0x0870.
Of course, this idea is only usefull when the address of the location of the load immediate instruction (0x0870) can be calculated. There are indeed jump (branch) instructions where this is possible. Note that the load immediate instruction could also be replaced by some other instruction (as long as it is not a jump/branch instruction). ## Saturday, April 7, 2018 |
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