SERVING THE QUANTITATIVE FINANCE COMMUNITY

Collector
Posts: 4411
Joined: August 21st, 2001, 12:37 pm

### Re: How many holes does a straw have?

YUM!!!!
There are between 3 to 6 holes in bread
brEad  3 holes
BrEad 4 holes
Bread 5 holes
BRead 6 holes

katastrofa
Posts: 8750
Joined: August 16th, 2007, 5:36 am
Location: Alpha Centauri

### Re: How many holes does a straw have?

Brilliant!

frolloos
Posts: 1617
Joined: September 27th, 2007, 5:29 pm
Location: Netherlands

### Re: How many holes does a straw have?

A straw is topologically equivalent to a donut. A donut has one hole. Therefore the straw has one hole.
Is it? I thought two spaces are topologically equivalent if one can be deformed into the other without ripping / cutting the surface.

Cuchulainn
Topic Author
Posts: 61129
Joined: July 16th, 2004, 7:38 am
Location: Amsterdam
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### Re: How many holes does a straw have?

A straw is topologically equivalent to a donut.  A donut has one hole. Therefore the straw has one hole.
Is it? I thought two spaces are topologically equivalent if one can be deformed into the other without ripping / cutting the surface.
I thought Topology was something that only existed in topologists' minds. What a pleasant, if not somewhat worrying surprise.
http://www.datasimfinancial.com
http://www.datasim.nl

Every Time We Teach a Child Something, We Keep Him from Inventing It Himself
Jean Piaget

Traden4Alpha
Posts: 23951
Joined: September 20th, 2002, 8:30 pm

### Re: How many holes does a straw have?

A straw is topologically equivalent to a donut. A donut has one hole. Therefore the straw has one hole.
Is it? I thought two spaces are topologically equivalent if one can be deformed into the other without ripping / cutting the surface.
Yes, that's the right definition.

Now take a donut ring of dough, put a thin rolling pin through the middle, and roll the donut into a tube. Elongate the tube and you have a straw!

frolloos
Posts: 1617
Joined: September 27th, 2007, 5:29 pm
Location: Netherlands

### Re: How many holes does a straw have?

A straw is topologically equivalent to a donut.  A donut has one hole. Therefore the straw has one hole.
Is it? I thought two spaces are topologically equivalent if one can be deformed into the other without ripping / cutting the surface.
I thought Topology was something that only existed in topologists' minds. What a pleasant, if not somewhat worrying surprise.
I only have homeomorphic dreams.

Traden4Alpha
Posts: 23951
Joined: September 20th, 2002, 8:30 pm

### Re: How many holes does a straw have?

Is it? I thought two spaces are topologically equivalent if one can be deformed into the other without ripping / cutting the surface.
I thought Topology was something that only existed in topologists' minds. What a pleasant, if not somewhat worrying surprise.
I only have homeomorphic dreams.
So you self-identify as a topologist?

frolloos
Posts: 1617
Joined: September 27th, 2007, 5:29 pm
Location: Netherlands

### Re: How many holes does a straw have?

That is a very category theory like question.

But no, not at all. It's fascinating, like so many other things in maths and physics, but I have no talent for it/them.

Cuchulainn
Topic Author
Posts: 61129
Joined: July 16th, 2004, 7:38 am
Location: Amsterdam
Contact:

### Re: How many holes does a straw have?

That is a very category theory like question.

But no, not at all. It's fascinating, like so many other things in maths and physics, but I have no talent for it/them.
I did topology at undergrad level from Cambridge PhD student of W. V. D. Hodge. But not my forte.
You're in the realm of Riemann and Poincare who eat straws for breakfast.
Unfortunately, constructing Cauchy sequences on a torus is very difficult.
http://www.datasimfinancial.com
http://www.datasim.nl

Every Time We Teach a Child Something, We Keep Him from Inventing It Himself
Jean Piaget

Cuchulainn
Topic Author
Posts: 61129
Joined: July 16th, 2004, 7:38 am
Location: Amsterdam
Contact:

### Re: How many holes does a straw have?

Is it? I thought two spaces are topologically equivalent if one can be deformed into the other without ripping / cutting the surface.
I thought Topology was something that only existed in topologists' minds. What a pleasant, if not somewhat worrying surprise.
I only have homeomorphic dreams.
What about automorphism, homomophism and diffeomorphisms?
Some of you? catamorphism?
http://www.datasimfinancial.com
http://www.datasim.nl

Every Time We Teach a Child Something, We Keep Him from Inventing It Himself
Jean Piaget

Cuchulainn
Topic Author
Posts: 61129
Joined: July 16th, 2004, 7:38 am
Location: Amsterdam
Contact:

### Re: How many holes does a straw have?

That is a very category theory like question.

But no, not at all. It's fascinating, like so many other things in maths and physics, but I have no talent for it/them.
http://www.datasimfinancial.com
http://www.datasim.nl

Every Time We Teach a Child Something, We Keep Him from Inventing It Himself
Jean Piaget

Cuchulainn
Topic Author
Posts: 61129
Joined: July 16th, 2004, 7:38 am
Location: Amsterdam
Contact:

### Re: How many holes does a straw have?

http://www.datasimfinancial.com
http://www.datasim.nl

Every Time We Teach a Child Something, We Keep Him from Inventing It Himself
Jean Piaget

katastrofa
Posts: 8750
Joined: August 16th, 2007, 5:36 am
Location: Alpha Centauri

### Re: How many holes does a straw have?

That is a very category theory like question.

But no, not at all. It's fascinating, like so many other things in maths and physics, but I have no talent for it/them.
Have you heard about the 10,000 hours theory?

(Why is an ellipsis popping up at the end of my posts? Some forum bug?)

...

frolloos
Posts: 1617
Joined: September 27th, 2007, 5:29 pm
Location: Netherlands

### Re: How many holes does a straw have?

That is a very category theory like question.

But no, not at all. It's fascinating, like so many other things in maths and physics, but I have no talent for it/them.
Have you heard about the 10,000 hours theory?

(Why is an ellipsis popping up at the end of my posts? Some forum bug?)

...
Haven't heard about it so looked it up. I think it works for certain "mechanical" activities only. I don't even have the 10,000 hours (yet): my manager expects me to be at work every day, and after work:

Cuchulainn
Topic Author
Posts: 61129
Joined: July 16th, 2004, 7:38 am
Location: Amsterdam
Contact:

### Re: How many holes does a straw have?

That 10K idea is based on Western ideology.

Learn from the mistakes of others, you may not live long enough to make them all yourself.
http://www.datasimfinancial.com
http://www.datasim.nl

Every Time We Teach a Child Something, We Keep Him from Inventing It Himself
Jean Piaget
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