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.
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:
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.
Daries of Doeschka MeijsingI finished reading the book En 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
Wednesday, May 16, 2018
Tuesday, May 15, 2018
BookAt 9:52, I bought the following two books from charity shop Het Goed:
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
Saturday, May 5, 2018
Friday, May 4, 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:
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.
BookAt 09:31, I bought the book Sur 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.
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
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.
AKI takes overIn the afternoon, I went to see the exhibition AKI takes over: "Hotel Bella Arte" at the University of Twente with works by Nils Leibeling and Jelle van Assem. our magnolia have fallen off. A tulip has opened in the back garden.
Wednesday, April 18, 2018
BooksAt 16:32:40, I bought the following two books from charity shop Het Goed:
China DreamsI saw the exhibition China 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.
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!
Addition Saturday, April 14: I got an email from Marcel informing me that I was the first one to have reported the Easter Egg and that even Walter did not know anything about it.
Cosey Fanny TuttiThis morning, I finished reading the auto-biography Cosey 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. 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.
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 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).
Trip to China 2010
-- contact -- Frans
My life as a hacker
The Art of Programming
HTML to LaTeX
eXtreme Programming Programs Hamilton cycles
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SGF files with
a total size of 85,019 bytes,
102 KML files with
a total size of 4,329,050 bytes,
and 2 EXE files with a total size of 38,340 bytes.
a total size of 640,918 bytes,
This leads to a total size of 99,516,370 bytes.