Sun Mon Tue Wed 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**

## Wednesday, March 10, 1999

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:

n | min | dimensions | left | square-left |

1 | 1 | 1 x 1 | 0 | 0 |

2 | 6 | 2 x 3 | 1 | 4 |

3 | 15 | 3 x 5 | 1 | 11 |

4 | 35 | 5 x 7 | 5 | 19 |

5 | 60 | 5 x 12 | 5 | 26 |

6 | 99 | 9 x 11 | 8 | 30 |

7 | 154 | 11 x 14 | 14 | 29 |

7 | 154 | 7 x 22 | 14 | 29 |

8 | 210 | 14 x 15 | 6 | 21 |

9 | 300 | 15 x 20 | 15 | 39 |

10 | 405 | 15 x 27 | 20 | 56 |

11 | 513 | 19 x 27 | 7 | 70 |

12 | 667 | 23 x 29 | 17 | 79 |

13 | 836 | 22 x 38 | 17 | 81 |

14 | 1035 | 23 x 45 | 20 | 74 |

15 | 1265 | 23 x 55 | 25 | 56 |

16 | 1512 | 28 x 54 | 16 | 25 |

17 | 1806 | 42 x 43 | 21 | 64 |

18 | 2142 | 42 x 51 | 33 | 100 |

19 | 2491 | 47 x 53 | 21 | 131 |

20 | 2900 | 50 x 58 | 30 | 155 |

21 | 3348 | 54 x 62 | 37 | 53 |

22 | 3906 | 62 x 63 | 111 | 174 |

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

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.

Home |
February 1999 |
April 1999.