"Peter Moylan" > wrote in message
. au...
> Jonathan de Boyne Pollard wrote:
>>>> That might explain it, I guess. So if I see something before me that I
>>>> am inclined to refer to as a "coffee cup", how am I to tell whether or
>>>> not it actually _is_ a coffee cup in some essential way?
>>>
>>> In fact, it could be your doughnut.
>>>
>>> (Old topology joke.)
>>
>> My doughnuts are generally not continuously deformable to coffee cups.
>> I'd have to poke them with a stick to make that true, and that would
>> squirt jam everywhere.
>
> Would topology have still been the field it is today if doughnuts had
> not existed?

All topology textbooks would contain pictures of coffee cups.

Or topologically identical people?

pjk