ABSTRACT

Of course, in grade school, origami can be used to enhance different kinds of skills and for many different purposes. But I am a mathematician and my workshop was in the math area, so I concentrated my attention on various mathematical aspects of origami. Now, it is true that when you do origami, you also do, whether you notice it or not, some kind of mathematics and you eventually absorb it. For instance, once you have folded a preliminary base from a square piece of paper several times, then you know that, when you halve the side of a square, the area is divided by four. So, if you received, as I did last year, a pizza ad saying:

maxi diameter 46 cm 18000 lira mezza diameter 23 cm 10000 lira,

you would notice immediately that the name “mezza”, which means half, is misleading and the price is unfair: If with a maxi pizza, you can feed four

292 E. Frigerio

people, then with a mezza, you would expect to feed two, while you actually can feed only one, and at a high cost! This example is quite obvious, but in general, the geometry underlying origami is more subtle; my main goal was to make it more evident.