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Diary, March 1999


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Wednesday, March 10, 1999

Squares and rectangles

This morning Annabel took a folded handkerchief, folded it open once, and said `This is a rectangle'. After folding it open once more, she said `And this is a square'. And again she folded it open, and said `This is a rectangle', and after folding it open completely, she exclaimed: `And this is a square'.

This proves that Annabel understands the abstract concepts square and rectangle. I am often astonished by what she understands, and what she remembers. Maybe this astonishment is caused by the fact that we as adults often cannot recall many memories from when we were very small. I wonder whether our children in this age of video cameras will be able to recall more early memories when they are older and seeing all those home videos from when they were young.


Thursday, March 11, 1999

Folding strips of paper

Today, I received some junk mail from the Dutch magazine `Elsevier'. Inside the envelop was something that looked like a miniature magazine. Opening, I discovered it was a long folded piece of paper displaying many of the covers from the past year. Some I recognized, others not. When I tried to fold it together again, I failed. Okay, I did fold it together, but it did not fit nicely as before. (A common experience many of us have, when trying to fold a large map.)

This made me wonder in how many ways a strip of paper, with folds, can be folded together, ignoring the final result, and also what would be the best strategy for finding that one (or more) ways to fold it nicely.


Saturday, March 13, 1999

What you can do with a straw or two

Every Saturday, we take our lunch at McDonald's in Enschede. I always order a Big Mac Menu, and a separate Big Mac.
Li-Xia and I eat the Big Macs, and Annabel eats the French fries (although I have to admit that I also take some). The cola we share among the three of us. I like to finish the iceberg lettuce that falls of the the Big Mac while I eat it, but I do not like to use my fingers. An alternative is to use some French fries, but today, I discovered that the best method is to use two straws as chop sticks.


Thursday, March 18, 1999

Squares inside rectangles

After having investigated squares in squares, the logical next step would be to investigate squares in rectangles. The table below gives a list of (possible) smallest rectangles which can contain the squares 1 to n:

nmindimensionsleftsquare-left
111 x 100
262 x 314
3153 x 5111
4355 x 7519
5605 x 12526
6999 x 11830
715411 x 141429
71547 x 221429
821014 x 15621
930015 x 201539
1040515 x 272056
1151319 x 27770
1266723 x 291779
1383622 x 381781
14103523 x 452074
15126523 x 552556
16151228 x 541625
17180642 x 432164
18214242 x 5133100
19249147 x 5321131
20290050 x 5830155
21334854 x 623753
22390662 x 63111174

I found a very elegant proof for proving that there exist no rectangle which exactly can be filled with squares from 1 to n, for some n. Time is lacking to write it down here.

(follow-up)


Wednesday, March 24, 1999

Cutting off my beard

Enough pictures have been taken of me having a beard in the past days. This morning I almost spend a quarter of an hour standing before the mirror cutting of my beard. My skin is no longer used to the appliance of a shaver.


Monday, March 29, 1999

House for sale

This is our (first) house. Currently, it is for sale, as we plan to move to Almelo, a city not far from Enschede, because soon we both will be working there.

(It is no longer for sale.)



Thursday, March 31, 1999

A goodbey present

Today, was my last day working with Tecnomatix, and as a goodbey present, I received an envelop, which contained a slip of paper with a
picture of the book Monet, or the Triumph of Impressionism by Daniel Wildenstein. The Monet Catalogue raisonné had not arrived yet, but it was on its way. You may have guess that the idea for this present was mine.


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