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Dairy, November 2017



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Wednesday, November 1, 2017

Are street tiling patterns Turing complete?

Today it is 56 calendar years ago that I was born, which means that I am born on a Wednesday. This is because 56 is twice 28 and it is a property of the Gregorian calendar that the days of the week repeat after 28 years (except when there is a century crossing involved that is not divisible by 400). I did not really celebrate my birthday.

Last week, I wondered whether it is possible to generate a possible infinite street tiling pattern without using back-tracking. I thought about starting with some row of a certain length and next generate rows below it as long as I wished. I was thinking about putting this into a JavaScript script inside a page and generate a random pattern on demand. I worked on a program to generate all impossible sequences to be found in a row and all impossible continuations from a part of a row to the next row. I think the program is correct, but I do not know how to convert the output into a state machine for generating a 'random' row below a given row. I even do not know if it is possible. Than it appeared to me that maybe Street tile patterns might be complex enough to be Turing complete.


Monday, November 6, 2017

Walking Through Walls

Early this morning, I finished reading the book Walk Through Walls: A Memoir by Marina Abramović and James Kaplan (as ghost writer, it seems), which I started reading on October 14 after I bought it on October 11. I actually really started reading the book from October 24. I found this quite an interesting book, mind blowing at moments. It made me also realize how much I already knew about her, first through the book The lovers, which I bought many years ago and also read, and later also through watching some videos about her and her performances. She also talks about her personal struggles and the many retreats she undertook remote areas, with Australian Aboriginal peoples, at buddhist monastries, and with shamans in the amazone. Many of these she describes as life changing. She also descibes her struggles when her second husband Paolo Canevari leaves her, actually twice, to a women who described herself as a sexual anthropologist, a woman with dead-white skin and red hair. Betony Vernon matches this description and there are also photos of her together with Paolo Canevari. However, from 2004 to 2014, Vernon was married to Barnaba Fornasetti. Canevari met with the woman at the Givenchy show in 2008 and in 2010, Abramović talked with the woman against the will of Canevari after he had returned to her. The woman told her: "He's addicted to me. He will always come back to me." And that is what happened. Probably the woman understood male sexuality better than Abramović, that she could make this statement.


Tuesday, November 7, 2017

Bottle ring

This evening at TkkrLab, another member made a bottle ring with the text ffaa5e with the of Blender and one of our 3D printers. The result is show on the top right.


Sunday, November 12, 2017

Infinite sequences

I discovered that my statement about street tiling pattern of the first of the month is incorrect. When I increased the length of the sequences to be investigated, I discovered that it did not stop at what I had thought. It seems the list of impossible sequences and chains is infinite. (A chain consists of two sequences that match with valid tiles.) I studied the impossible sequences for a general pattern, but did not discover one. I did noticed that sequences and chains where not really symmetric and realized that this has to do with the encoding method of the street tiles, which all start with an 'A' in the left top corner. This gave me the idea to give eacht street tile its own encoding letters, using the following encoding:
  a bc

  d fg jkl
  e hi mno

    pq ABC
    rs DEF
    tu GHI
This resulted in only a limited set of chains (only with length two) to be impossible. But it seems that there are still infinite impossible sequences. I started visualzing the sequences with embedded JavaScript below and only leaving the characteristic sequences:
This text is displayed if your browser does not support HTML5 Canvas.

It looks that for each length, there are only a limited number of patterns, if we look at the the depth at which the piece extend down. I have selected one pattern for each of them. I also worked on constructing grammar (so far only a regular expression) to match all the patterns.


Monday, November 13, 2017

Bike stolen

At 17:30, I arrived at charity shop Het Goed and looked around the book section. When I came outside around 17:50, my Urban HPV bike, which I got on Wednesday, March 9, 2011, was gone. I spend some time looking around, considering the possibility that I was mistaken about the place wheren I had placed it. I went inside to ask if it happens more often that bikes are stolen in front of the shop. They had only heard about an electric assisted bike being stolen. The bike was already getting old, but at the beginning of the summer the transmission had broken down and was replaced by a new one. I was counting on using it for another three years before it being replaced. I have not much hope of getting the bike back, as usually they are transported to East Europe and sold there. I did report the bike as being stolen when I arrived at home. I will miss all the extra things: The two horns (on a gift from Annabel, the other found in the attic), the three induction lights, and the two yellow CYBER stickers.


This months interesting links


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