# ^^Spazio metrico. Distanza in uno spazio metrico.

## Librosito

Tipi di distanza
nel piano cartesiano.

Sfera in uno spazio metrico. Sfera bucata,
aperta, chiusa.

## inet

wp/Signed_distance_function

# Storia

1906 L'inventore degli spazi metrici e' Fréchet, nella sua tesi di dottorato.

1914 Il nome e' pero' dovuto ad Hausdorff nel suo lavoro di topologia.

wp/Maurice_René_Fréchet

## Fréchet's generalized theory of limits

... applies to many sorts of spaces, including vector spaces, but is not ...
confined to those spaces in which the elements may be regarded as steps
[vectors]. On the other hand, this geometry of steps constitutes a very
important part of Fréchet's general theory and was worth solidifying with an
appropriate set of postulates. Fréchet had not done this, nor did he consider
these particular vector systems as peculiarly important . . . .

I gave a full set of axioms for vector spaces. Fréchet liked it, but did not
seem particularly struck with the result. But then, a few weeks later, he became
quite excited when he saw an article published by Stefan Banach ... which
contained results practically identical with those I had given, neither more nor
less general . . . .

Wiener autobiography.

cit:
The axiomatization of linear
algebra: 1875-1940. pag.42