


Let functions f: X -> Y
and g : Y -> X
be injective.
Horseshue would represent the set Y\f(X)
and a ractangle the set X\g(Y).
The bijection is an identification of a set of horssue and its all images via fg with set of images via g of all those horseshues. Simillarilly we can identify a pyramid of ractangles with its back image of f (the smaller pyramid). It looks as a translation on the pyramid of ractangles, just like in Hilberts Hotel (every one goes to his neighbour) and there is infinity of them.

Study of perspective on curved spaces.


