Today, I read an article about two cases of H1N1 virus in Las Vegas.
In itself this is not special, except that sub title reads:
"Neither patient had traveled or knew anyone who had flu."
Further on it says: "We've been testing people looking for
additional family members or close contacts that are infected
but haven't found it." This means that these two people picked
it up on 'the street'. And that can only mean that the flu is
already circulating without being noticed, probably through
'mild' cases where people don't even realize that they have
the flu. If it is the case like this in Las Vegas, it must be
the case in many other places in the world.
This evening, I biked to the university to play Go. When I arrived there were some people playing
music in the bar. I found Rudi and Taco just having started
a game and I decided to watch it. There were not many
people watching the people making music. It also seemed like
they took a long time to play which song next, and once a
while some new people would jump on the stage. Around eleven,
it suddenly became much busier and some new "band" entered
the stage. Rudi and Taco where playing their last Ko, where
the Ko threats of Rudi where related to a rather complicated
life-and-death problem in a corner. When we left, I found
a paper stating that from 20:30 to 23:00 was free jamming,
and 23:00 to 23:30 was a performance of the
The High Daggers. We left about half way the performance.
This afternoon, I went to see the movieStar Trek. I had already bought my ticket yesterday,
but that was a little optimisic because there were only nine people
(including myself) in the room. But maybe this has to do with the
fact that 12:40 is not the usuall time that people of my age go to
watch such a movie. I found it a great movie, the best Star Trek
movie that I have watched, and that is not because of the special
effects. The movie made me laugh several times, not because of jokes,
but of the strong lines. The characters in the movie match very well
with those in the original series. Really a great movie.
This evening, I discovered that an idea for a simple heuristic
for solving an Exact Cover problem,
proofed to be rather poweful. The idea is to select that vector
for which the inner product of the vector with a vector counting
the number of vectors that have a one in the given column.
Here is the program that
implements this heuristic.
This weekend, I spend some more time investigating the fastest
algorithm to solve the Exact Cover
problem. To my surprise, one of the most trivial heuristics, gives
the best results so far.
This heuristics consist of simply selecting the first remainding
vector for the first position that has a minimum number of covering
vectors. (I guess that the words "first" can be replaced by "random"
in the last sentense, because both are determined by the order in
which the problem is stated in the input file.) The implementation
can be found here.
Last night I spend some hours analyzing an interesting
death-or-alive problem that came up during
a game of Go that I have
been playing on Its Your Turn. The problem is shown on the right.
It is blacks turn. Here the SGF-file with a record of my game played so far,
and my answer to this position, followed by an analysis
of all possible continuations by white, and how to
respond to these. I hope that I did not miss anything.
It was an interesting exercise.
In the summer of 1978, probably on Saturday, July 29, 2009,
I bought a "Beat the Computer No.24" puzzle game from
I have never been able to solve this puzzle by myself. Some
weeks ago, I showed it to Annabel
and for one hour, as part of a bet, she tried to find a solution,
but she failed. I again played with it for some time. Yesterday evening,
I started writing a program
to transform the puzzle into a Exact Cover. This program produced 15128 vectors with
192 positions. I used the UNIX sort command to remove all double
vectors, which resulted in 13040 unique vectors. When I fed this
into the Exact Cover program I wrote last
Sunday, I was really surprised that it started to spit out
solution by about seven or eight per second. I had expected that
it would take some hours to find only a single solution. I had
thought that I would have had to improve the "trivial" algorithm
to make it find sufficient numbers of solutions, but it looks like
there is no need for it yet.
This evening, I went to the university to play Go. After Taco and Rudi arrived, I showed them
the game, I had been playing on Its Your Turn.
They showed me a move that I had not considered yet, which might
still spell disaster for me. I first played a game against Rudi
(while he also played against Taco) with seven stones ahead.
When he managed to kill a group, I resigned. Meanwhile Huub had
arrived and I played a game against him where he got three stones
ahead. It looked like I was going to lose the game, but at the
end Huub made some accidential mistakes and when I could kill
one of his groups, he resigned. At home I analysed the (Its Your
Turn) game a little further and I found a good counter move to
the problematic move Rudi and Taco had shown.
The updated game record including
some comments by Rudi and Taco.
This morning, I finished reading the book
Pooh and the Philosophers by John Tyerman Williams in which
I started reading on 16 april, the same day, I
bought the book from De Slegte at
15:23:35 for € 5,90. Honestly saying, I did not think
that this is a very good book. I even thought about putting it down
before finishing it. I feel it is very much like the style of
Bluff Your Way in Philosophy, a book that supposedly
should give you some basic understanding of philosophy but in
reality is full of inside jokes that can only be understand by
those that already have some knowledge about the subject. But
what even disturbes me more about this book is the fact that the
author takes the position that Pooh, a Bear of Little Brain, in
reality is the greatest philosophical thinker in history. This is joke
that soon gets boring. Some people find it a very funny book.
In this sense this books differs from the other spin-off books
(like The Tao of Pooh and Winnie-the-Pooh on Problem Solving)
that show how Pooh and the other characters in the book unconsciously
apply certain principles.
This evening, I went to the university to
play Go. When I arrived, Rudi
and Taco where already playing a game. I watched them
for some time and then agreed with Rudi that he would
play against me simultaneously with a seven stone
handicap. Right within the first twenty moves, I lost
some stones. In the end I lost with twenty points.
Then I followed the game between Rudi and Taco till
the end, after which we went home quite soon.
Tonight was museum night. I decided to visit Rijksmuseum Twenthe in Enschede because I had read somewhere that the
entrance was free and I wanted to see the painting by Monet. The last time I visited the museum on Sunday, August 3, 2003 together with Annabel, it was not on display. When I arrived, I discovered that the
museum was only free for people with a button from the
Balenfestival and that
that button costed 5 Euro. I decided to buy it and walked through the
museum. Hereby a list of paintings that I found interesting: