Re: Isometries of closed disks

William Elliot <[EMAIL PROTECTED]> escribió en el mensaje
 news:[EMAIL PROTECTED]:

> On Wed, 3 Dec 2003, Jose Carlos Santos wrote:
>
>> Each closed disk in the plane has the following properties:
>
>> 1) it's compact;
>> 2) its interior is non-empty;
>> 3) its boundary is connected;
>> 4) its group of isometries is infinite.
>>
>> My question is: are closed disks the only plane sets with these
>> properties. My guess is that the answer is yes.
>
> Do closed filled squares, rectangles and ellipses have those
> properties?

No, its groups of isometries are finite.


-- 
Best regards,

Ignacio Larrosa Cañestro
A Coruña (España)
[EMAIL PROTECTED]