Previous Up Next

Diary, July 1996

 Sun Mon Tue Wen Thu Fri Sat

       1   2   3   4   5   6
   7   8   9  10  11  12  13
  14  15  16  17  18  19  20
  21  22  23  24  25  26  27
  28  29  30  31

Monday, July 1, 1996

People standing in a circle

In a reply to a posting about
People standing in a circle, Kilian Heckrodt wrote: And Brian M. Moore wrote:

Old Chinese cameras

Last Saturday, I paid a visit to a second hand camera shop, and mentioned that I was going to China. Immediately, the owner said that he had just got a book with old Chinese cameras, and he made a list of cameras that he is interested in:

KLM flies to Beijing

Yesterday, KLM made the first official flight to Beijing. That means we will be on the 9th (official) flight of KLM to Beijing. We might even fly with the `City of Beijing' plane, whoes name was revealed in Beijing.

Wednesday, July 3, 1996

IQ and personality tests

I did the
The Kingdomality Personal Preference Profile test (from Career Management International, Inc), and found out I am a shepherd. Funny, but that is not what I had expected.

I found this page through the 2H home page with IQ, personality and entrepreneurial tests.

Wednesday, July 10, 1996

Meike Vernooy

Meike Vernooy is a very bright girl, who wants to study medcine at the Erasmus University in Rotterdam, actually she already has been going there in the past year. Here average grade on the final highschool examinations was about 9.5 (on a 1 to 10 scale). The Erasmus University had offered her a place by-passing the numerus fixus (a lottery system unaware of grades which is applied if there are two many students applying for a certain course). However, our Minister for Education, Mr Ritzen, decided this was illegal.

I am tempted to conclude from this that I live in a country that discriminates bright people, just because they are intelligent. The whole scholing system pays alot of energy in the low 5% of the students, but seems to be totally unaware of the upper 5%, as if it is a crime to be bright.

Thursday, July 11, 1996

Reverse billing

Did you ever have to pay for not receiving something? It is possible on the internet. See what I read at the bottom of a commercial advertisement in the
alt.books.cs-lewis newsgroup:
Notice To: Newsgroup Moderators, Managers or Vested Interest Subscribers.
Due to HLD PUBLISHING limited list of Newsgroups, it is not our policy to
remove a newsgroup from our list free of charge. To be removed from our
list of future commericial postings by HLD PUBLISHING COMPANY an Annual
Charge of Ninety Five dollars is required. Just send $95.00 with your
Name, Address and Name of the Newsgroup to be removed from our list.
Furthermore, HLD PUBLISHING COMPANY reserves the right to cancel its own
postings. Cancellations of our postings performed by outside parties will
be charged a Ninety Five dollar fee per cancellation.  A bill with proof
of cancellations made will be sent to all parties involved, plus, it will
automatically be sent to Attorneys Specializing in Collections nationwide
and worldwide. HLD PUBLISHING COMPANY will protect and maintain its interest.
I wonder who owns this newsgroup. Or should I charge them for posting unwanted commercial ads? (Was announced as spam)

A programming Challenge

Mark G. Rodenkirch posted the follong challence in comp.programming.contests.)

For those of you interested in using programs to solve problems, here is one I first saw a number of years ago in Games Magazine.

It is a fact that: 1^2 + 2^2 + ... + 24^2 = 70^2

Treat these as squares of size 1x1, 2x2, ..., 23x23, and 70x70. Place as many of the smaller squares into the 70x70 square to fill as much of the 70x70 square as possible without the smaller squares overlaying one another.

What is the maximum area of the 70x70 square that can be filled?

The idea is to write a program to solve this problem. I really don't have any good ideas about how to solve this problem using C or any other language. I would like to see any solutions posted to this group.

If you want to do this through a program it should be a program which tries to fit in the squares one by one, and uses a back-tracking algorithm.

But as there are so many ways to fit in the squares, it is impossible to find the maximum by trying all possibilities. Still I think it is possible to find a solution which comes close to the maximum.

Obviously you should start with the biggest squares, as that square takes up the most space. From there on you will try one smaller and so on.

For each square you want to place, you have to decided whether you are going to place it or not. It might be possible that with leaving out the 23x23 square you can place all the other sqaures, whereas putting it in, will force you to leave other squares out which might have a greater surface then 23x23. (If it is impossible to place a square at all you are forced to skip it.)

If you have decided to place a square, there are still many positions left, at which you could place it. Of course, you want to place it at a good position. A good place would be a position which would allow most of the other squares to be placed.

Now you have to come up with an algorithm for determing which is a good place to put the square. You do this by placing the square, and for all of the smaller squares you are going to check all the positions at which they can be placed. For each of this positions you add up some value depending on the size. The total sum of this gives you a rating. I would use x^2 (where x equals the size) as the way of calculating the value to be added.

After you have calculated the rating for all possible placings, you are going to try them one by one. This program will return many solutions. You just have to let it run as long as possible, and only keep the best solutions found so far.


On cutting an Apple

With 3 straight cuts (without moving the pieces) you can cut an apple in 8 pieces. With 4 cuts you can cut it in 15 pieces. What is the general formulea for this? I already had figured this out, some time ago (see my statements page), by giving a recurrence equation.

Emmanuel Gaillot found the following formulea for this (as posted on rec.puzzles):

    ____ n
     \          p!
     /     -----------
    /       i! (p - i)!
    i = 0

In which n stands for the dimenstion, and p for the number of cuts.

Someone playing the trumpet

Finally, something interested around here happened. Some one started to play the trumpet while sitting on a bench at the entrance of the building. I walked over to the window to look. The sound echoed between the building and sounded very clear.

Friday, July 12, 1996

Symphony No.10

I am listing to
Symphony No 10. e-moll Opus 93 from Dmitri Shostakovich. I borrowed this CD from my good friend Meindert, with an option to buy it, if I like it. I think I am going to buy it.


Meindert's birthday

Meindert phoned me to tell me that it was his birthday, and asked us to come to his birthday party that evening. (Li-Xia was a little upset that we did not bring a present.) We stayed until a quarter past 11, while Annabel should already have been sound asleep.

It was a very nice evening with some philosophical discussion (Meindert just got his philosophy (master) degree a few months ago, and one of the other friends is doing his Ph.D in philosophy, and the third friend is an artist, who made the art work (not: illustrations) for Meindert's master thesis), and drank some Belgium beer from a 3 liter bottle that Meindert had bought 3 years ago. The cork came out with a mild plop, and the beer had a very nice taste. Li-Xia and Meindert discussed some Chinese recepies, as Meindert loves cooking.

( follow-up)

Going to China

Yesterday, I received my passport in the mail with the visas for Annabel and me inside. But on closer look, I found two visas, one with a `Cancelled' stamp on it. They had made some mistake, and corrected it. I hope this is not going to cause any trouble at the border.

We also bought an additional suitcase yesterday evening, which has a not-so-bright red colour.

Sunday, July 14, 1996

A programming Challenge

The Challenge was to write a program that would try to fit as many as possible of the squares with sizes 1, 2, .., and 24 in a square with size 70. I wrote a program to do this, and found a solution which includes all squares except the square with size 10.

The program uses a back-tracking algorithm, but is simpler than the solution I described before. It only tries to place squares in corners (made by the other squares and the outside of the big square). To test whether a square can be placed, it is sufficient to check whether the corner positions are free, because the squares are placed in decending order. The algorithm also has a cut-off build in which prevents the program to try solution for which it is known that they cannot result in a better solution than the one found sofar.


Monday, July 15, 1996

IQ tests

This morning I received an email with a pointer to a
Free, Fast & Fun IQ Test. The email said: Try this! It's quick, makes you laugh, and reports immediately an accurate score! I took the test, and then found out that I had to pay $14.95 to receive my Complete Personal Intelligence Profile. I was satisfied with knowing my general score. (If you tell me yours, I will tell you mine.) The results are stored in their database, so I can still send them a money order.

Wednesday, July 17, 1996

Going to China

Today we received a letter from Uncle Lin in Beijing. After phoning him we found out that they already have bought the tickets, and will meet us at the airport at 11 o'clock on July 28 to hand us the tickets. They also offered us to stay with them while we are in Beijing.

A programming Challenge

Thomas Wolf wrote in a newsgroup posting: Which proves that my algorithm is not finding the best solution known. But Thomas did not explain how his solution was found in the posting, so I send him an email saying: And he replied: He got this solution from the geometry section of the rec.puzzles archive.


Thursday, July 18, 1996

A programming Challenge

The story continues. This morning I received another email from Thomas Wolf, which said: It seems to me that it still would be a good strategy to first try those placements which do not create any narrow corridors. Also, because we know a good solution, we good force the program only to search to solutions that are equally good or better, creating a stronger cut-off.

After seen the best known solution, I have been thinking about a different strategy. Maybe the program should not start with the biggest square first, but fill up empty squares from the inside to the outside, and for each empty (1x1) square try to find the best fitting square.

Thomas Wolf also created a page about this problem.

Going to China

Today we have changed some guilders to Dollars, both cash and American Travel-checks. The exchange rates have been changing rapidly in the past days.

We have been busy some days with packing the suit-cases. If you travel to relatives in China, it means you have to bring a lot of presents. If we didn't take any diapers with us, probably half of our load would have been presents.

Friday, July 26, 1996

Yesterday evening I got this special holiday feeling, that I haven't had for a long time. A feeling of relaxing, knowing that you can leave behind all the things at home, and go away. But I still had to work one day after being ill for some time (a flue).

Tomorrow we are flying to China. Our suitcases are packed, yesterday evening we checked all the papers (including the money and travel cheques).

Monday, July 29, 1996

This is our first day in Urumqi while staying with our family. Yesterday, we spend our first day in China on the Beijing City International Airport, of which three hours in
the plane, which could not take of because of a `thunderstorm'.We arrived at about 10 o'clock (Beijing Time) in Urumqi. Although they use Beijing time in Urumqi, they are about two hours behind, as Urumqi is 2631 Km west of Beijing.

We haven't gone outside, but from our car trip from the airport to home, I know that many things have changed compared to our previous trip in 1993, when we came here on our honeymoon. Many things look more mordern, but I get the feeling that much of the rubbish remains. The distance between poor and rich is becoming more obvious. Just on the otherside of the street outside the compound we are staying on they are building a sky-scraper of 36 floors.

Xuan Xuan, my 7 year old nephew is watching me type this on the T1000 laptop I have brought with me.

Wednesday, July 31, 1996


This evening I managed to get my Toshiba T1000 laptop working again. Yesterday evening I found the source of all the problems with the bataries that seem to get worse and worse. The problem was not with the batteries but with the cable of the power-supply. This evening I managed to repair the cable, a small hardware hack, as the soldering tool was rather weak for the soldering tin I was using.


Taking a shower

Today, the water pressure is high enough to take a shower. The water heater is rather primitive, and does not operate properly if the water pressure is to low. The shower itself is also rather primitive: I cannot stand straight, and the showerhead is also too low for me. Luckly, it is still very hot, so there is no problem with getting cold. I think I have to get ready now, to take a shower when
Li-Xia is ready.

Home | June 1996 | August 1996.