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Sundew
This weekend I am attending an informal Go
weekend in Appelscha. Yesterday evening, I played one game against
a 6K player with five stones ahead and I won with 45 against
23. Then I also played some Havannah games with Ton, currently
one of the strongest players on Little Golum, a turn based playing site. This morning,
I went walking with him and someone else through woods, heather,
and sand drift. On the way back, Ton noticed that there was
sundew on
the path we were using. I took some pictures. We walker for
more than two hours and about six miles. (See KML file viewable in Google
Earth or in Google Maps.) This afternoon, I played a game against
Ton with five stones ahead but resigned after I lost a small
group. We continue to play anyway and I lost with 54 again 17.
Transit of Venus
I bought some second hand "Eclipse Shades™" from
Rainbow Symphony, Inc
distributed by Urania, a
public observatory in Belgium. I set my alarm at a quarter past
five, only to discover that it was too cloudy to see anything
from the
transit of Venus.
Prometheus
This evening, I went to the movie:
Prometheus. I found it an interesting movie, not much
like many the other action packed Science Fiction movies.
At some points it even rather slow. The plot is rather
complicated, maybe a little too complicated, which makes
reason for many plot holes. It is a good movie, but not
a match with Alien.
What is a Mind?
This morning, I finished reading What Is a Mind?: An
Integrative Introduction to the Philosophy of Mind by Suzanne Cunningham
(ISBN:9780872205185), which I started reading October 27, 2011,
after I bought the day before from bookshop Broekhuis for € 9 (with 50% off). It took me a long
time to finish this book, because it is not a very easy book. I found it
interesting, but some chapters left me a little disappointed. Chapter 2 is
rather shallow with respect to the treatment of the zombie argument.
Chapter 6: "Could a Machine Have a Mind" is mostly about the two approaches
to artificial intelligence: symbolsystem theories (the linguistic model)
and connectionism (neural networks). I had expected some reference to
Gödel,
Escher, Bach. In the additional resources in the back of the book, it
does mention The Mind's
I: Fantasies and reflections on self and soul. Chapter 7: "How Do We
Link Behavior to Mental States?" does not deal about the question how we can
know if others are conscious about ourself, but goes in great length to
discus TheoryTheory and Simulation Theory, which to me seems to be two ways
of describing the same thing. To me the book is a little too much from a
descriptive approach to philosophy, which seems to be more focused on
describing the development of ideas than an analytical approach. This however
is true for a lot of philosophy.
Jugo Flower
Last Friday, I got an email from Henk Koppelaar with the question if
Jugo Flower puzzle is more complex than the
Rubik's Cube.
It seems that it has less possible states than the cube, and also the
'movements' can be performed in any order. But that does not necessary mean
that it is easier to solve. If I understand it correctly, it means that you
have to find a combination of the binary vector 100100001001000 and
its fourteen rotations that when added modulo 2 result in the given problem
vector. Last Friday, I already wrote some programs, but yesterday evening, I
started to think about it with pen and paper. This morning, I discovered the
following things. First if we combine the vectors rotated 0 and 8 positions
we get:
100100001001000 (0)
010010001001000 (8)
110110000000000 (0+8)
If we combine the vector 2+8 with copies that have been rotated 1 and 2,
we get:
110110000000000 (0+8)
011011000000000 (1+9)
001101100000000 (2+10)
100000100000000 (0+1+2+8+9+10)
If we combine this vector with a copy that is 6 rotated, and rotate
the result over 3 positions, we find get:
100000100000000 (0+1+2+8+9+10)
000000100000100 (6+7+8+14+0+1)
100000000000100 (2+6+7+9+10+14)
100100000000000 (5+9+10+12+13+2)
This leeds to the interesting observation that the puzzle consist
of three independent puzzles, each consisting of five positions that
are three places apart. Furthermore because the number of 1values
is always even and various possible rotations, there are in fact
only three essential different configurations to deal with:
1__1__0__0__0__ (2+5+9+10+12+13)
1__0__1__0__0__ (0+1+2+8+9+10)
1__1__1__1__0__ (6+7+14)
This means that with a little memorization, and some practice, it is
relatively easy to solve this puzzle by hand with at most 18 movements.
With a simple computer program, it is possible to find solutions with
less movements by simply trying out all 2^15 possible combinations.
Jugo Flower variants
After yesterday, I started to think if there would be another pattern
like for the Jugo Flower which would make
more difficult to solve. I started to write a program that could count
the average number of moves needed to solve any problem for a given
pattern. The first implementation of the program was rather slow and I
noticed that it returned many the same values. That made me think about
the fact that many patterns are the same, if you rotate them. This
morning, I remembered that it is also possible to shuffle a pattern by
making steps. For example, the original pattern 100100010010000
can be reshuffled by taking each eleventh (modulo fifteen) value into
101101000000000. I noticed that the average number of moves
that is needed to solve any problem is directly related to the number
of positions that can be reached from the neutral position, which is
actually not that strange. For example the 110001000010000
pattern has four times as many solutions that can be reached than the
original pattern. I extended the program also with a check if the
puzzle can be split into a number of independent puzzles and how many
numbers one would have to memorize. For the original pattern this was
fifteen, twice six and once three moves. It appears that for the
example pattern can be viewed as five independent puzzles which only
require two numbers to be memorized. Which makes it a rather simple
puzzle to solve. The more positions can be reached, the more likely
that the puzzle consists of independent puzzles. Which makes the
patterns that can reach less position more complicated. According to
this reasoning, the pattern 101001001000000, which can only
reach 1023 different positions form the neutral position, is one of
the most interesting patterns. The version of
the program and its output that I
used find these result.
Peter Struycken: Three books
Three books about Peter Struycken that I had
ordered early from two bookshops arrived in the mail. From Jonas Kunstboeken, I received Struycken Structuur<Elementen 19691980 by P. Struycken,
catalogue of the exhibition held
from December 12, 1980 till January 25, 1981 in Museum Boijmansvan Beuningen in Rotterdam. I bought this for € 7.00.
From Antiquariaat Frans Melk, I
received Forum, Architectural Quarterly,
issue 35/5, June 1992 from Architectura et Amicitia (for € 14.00) and p. struycken. Eight paintings 1988
(for € 15.00). This last one is rather small, at first I thought
it was some addition to the other book. Inside it reads: "the end of the
comfortable painting", "the series of eight paintings are small sections
of an infinite space. in the same place in that space eight different
interference patterns were generated, each with three different waves.",
and "material autocryl, autoflex and matt varnish on perspex elements
on sheet of perspex in a greypainted steel frame 203x136 cm".
Dutch heroes
When I arrived at bookshop De Slegte,
I noticed two people who were handing out fliers for "Hollandse Helden
Weken" ("Dutch Heroes Weeks"), a campain by the bookshop related to
the merging with Selexy. Both bookshop chains have been bought by
investor ProCures who has plans to join the shops where possible. I am
a little afraid that De Slegte in Enschede will also be transformed.
Bookshops are going through a difficult time, but De Slegte is still
doing fine. In the Netherlands we have a law on fixed book prices,
which means that for one year a book cannot be sold under the price
established by the publisher. After this year, books are often dumped
below the fixed priced, as remaindered books (ramsj in Dutch).
De Slegte is selling such books and second hand books. Since about
half a year they are also selling the top 100 bestselling books for
the fixed price. Today, I bought:
 GodKeizer op Duin (God
Emperor of Dune) by Frank Herbert (ISBN:9789029014076) for
€ 7.95.
 Brieven (Letters) by John Keats (ISBN:9789025327620)
for € 5.00.
 Henry en June by Anaïs Nin (ISBN:9035111893) for
€ 2.50.
I got a € 2.50 reduction by the use of a coupon that
I received on Wednesday, May 23,
which can be used when you spend at least 15 Euro. I also enlisted
for the digital newsletter of Selexyz and De Slegte, which entitled
me a free book from ten different books. I selected Groeten van
Rottumer plaat (ISBN:9789046806241) in which a hunderd and some people
write about their favourite album. At home, I discovered that I
already owned a version of Henry en June. Next Monday, I will
try to swap it for another book from the sale.
Hamiltonian paths
Yesterday, Anand Krishnamoorthi contacted me with respect to
Counting Hamiltonian paths. He send me
his C++ path counting program
(published with permission) based on his solution for the Quora Data Center Challenge puzzle. The program is rather
similar to the one that I wrote. Mine constructs a transition
matrix between rows, while his calculates the transition over
and over again for each following row. I think his program is
better if you want to calculate the number of Hamiltonian paths
in a square grid, while mine is designed for calculating the
sequence with a fixed size and the recurrence equation for it.
Once the transition matrix is constructed, calculating the
sequence goes very vast. My program is 'breaking down' at about
size 12, he wrote today that his program: "can't yet handle more
than 18 vertices in a row." (My program took 7 minutes and 37 seconds
to calculate sequence for size 12 and about 66 minutes to
calculate sequence for size 13.) He also send a reference to
the article Exact
enumeration of Hamiltonian circuits, walks, and chains in
two and three dimensions.
Exchange books
I exchanged two books at bookshop
De Slegte for two other books. The books that I handed in
are Henry en June, which I bought on Saturday, June 15, and Er was eens een God, which I
got for free on Wednesday, May 23.
The first book I was allowed to change because I bought it less
then 14 days ago. And for the second I used a coupon I got with
the book Groeten van Rottumer plaat, which I got for free
for enlisting myself to some email list, because this book was
also one of the books you could choose from. The coupon gave
you the right to exchange the book. The two books I got from
the sale are:
 Een jaar als (g)een ander by
Kristien Hemmerechts (ISBN:9789045011240).
 Attaque! by Miquel Bulnes. (ISBN:9789044609233)
Both costed € 2.50. These where the two books I
liked most, but I probably would not have bought them, would
I not have wanted to get rid of the other books.
Peter Struycken
I received the two booklets that I ordered last week from
JOOT BOOKS Just Out Of Time
which are related to expositions of Peter Struycken. These are:
Mulisch: Poetry and drama
I went to bookshop Kruimeltje, where
they had a sale: 50% of for all the books on the second floor. I went
to look at the books they had about Harry Mulisch and I selected the
following two (prices after reduction):
 Theater 19601977, (ISBN:9023430433) for € 6.50,
drama.
 De vogels: Drie balladen for € 5.00, poetry.
This months interesting links
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