Fwd: [Haskell-cafe] Category Theory woes

2010-02-18 Thread Michael Matsko

- Forwarded Message - 
From: Michael Matsko msmat...@comcast.net 
To: Nick Rudnick joerg.rudn...@t-online.de 
Sent: Thursday, February 18, 2010 2:16:18 PM GMT -05:00 US/Canada Eastern 
Subject: Re: [Haskell-cafe] Category Theory woes 




Gregg, 



   Topologically speaking, the border of an open set is called the boundary of 
the set.  The boundary is defined as the closure of the set minus the set 
itself.  As an example consider the open interval (0,1) on the real line.  The 
closure of the set is [0,1], the closed interval on 0, 1.  The boundary would 
be the points 0 and 1. 



Mike Matsko 


- Original Message - 
From: Nick Rudnick joerg.rudn...@t-online.de 
To: Gregg Reynolds d...@mobileink.com 
Cc: Haskell Café List haskell-cafe@haskell.org 
Sent: Thursday, February 18, 2010 1:55:31 PM GMT -05:00 US/Canada Eastern 
Subject: Re: [Haskell-cafe] Category Theory woes 

Gregg Reynolds wrote: 


On Thu, Feb 18, 2010 at 7:48 AM, Nick Rudnick  joerg.rudn...@t-online.de  
wrote: 



IM(H??)O, a really introductive book on category theory still is to be written 
-- if category theory is really that fundamental (what I believe, due to its 
lifting of restrictions usually implicit at 'orthodox maths'), than it should 
find a reflection in our every day's common sense, shouldn't it? 



Goldblatt works for me. 
Accidentially, I have Goldblatt here, although I didn't read it before -- you 
agree with me it's far away from every day's common sense, even for a hobby 
coder?? I mean, this is not «Head first categories», is it? ;-)) With «every 
day's common sense» I did not mean «a mathematician's every day's common 
sense», but that of, e.g., a housewife or a child... 

But I have became curious now for Goldblatt... 








* the definition of open/closed sets in topology with the boundary elements of 
a closed set to considerable extent regardable as facing to an «outside» (so 
that reversing these terms could even appear more intuitive, or «bordered» 
instead of closed and «unbordered» instead of open), 

Both have a border, just in different places. 
Which elements form the border of an open set?? 









As an example, let's play a little: 

Arrows: Arrows are more fundamental than objects, in fact, categories may be 
defined with arrows only. Although I like the term arrow (more than 
'morphism'), I intuitively would find the term «reference» less contradictive 
with the actual intention, as this term 


Arrows don't refer.  
A *referrer* (object) refers to a *referee* (object) by a *reference* (arrow). 







Categories: In every day's language, a category is a completely different 
thing, without the least 

Not necesssarily (for Kantians, Aristoteleans?) Are you sure...?? See 
http://en.wikipedia.org/wiki/Categories_(Aristotle) ... 




  If memory serves, MacLane says somewhere that he and Eilenberg picked the 
term category as an explicit play on the same term in philosophy. 




In general I find mathematical terminology well-chosen and revealing, if one 
takes the trouble to do a little digging.  If you want to know what 
terminological chaos really looks like try linguistics. 
;-) For linguistics, granted... In regard of «a little digging», don't you 
think terminology work takes a great share, especially at interdisciplinary 
efforts? Wouldn't it be great to be able to drop, say 20% or even more, of such 
efforts and be able to progress more fluidly ? 




-g 



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Re: Fwd: [Haskell-cafe] Category Theory woes

2010-02-18 Thread Nick Rudnick

Hi Mike,

so an open set does not contain elements constituting a border/boundary 
of it, does it?


But a closed set does, doesn't it?

Cheers,

   Nick

Michael Matsko wrote:


- Forwarded Message -
From: Michael Matsko msmat...@comcast.net
To: Nick Rudnick joerg.rudn...@t-online.de
Sent: Thursday, February 18, 2010 2:16:18 PM GMT -05:00 US/Canada Eastern
Subject: Re: [Haskell-cafe] Category Theory woes

Gregg,

 

   Topologically speaking, the border of an open set is called the 
boundary of the set.  The boundary is defined as the closure of the 
set minus the set itself.  As an example consider the open interval 
(0,1) on the real line.  The closure of the set is [0,1], the closed 
interval on 0, 1.  The boundary would be the points 0 and 1.


 


Mike Matsko


- Original Message -
From: Nick Rudnick joerg.rudn...@t-online.de
To: Gregg Reynolds d...@mobileink.com
Cc: Haskell Café List haskell-cafe@haskell.org
Sent: Thursday, February 18, 2010 1:55:31 PM GMT -05:00 US/Canada Eastern
Subject: Re: [Haskell-cafe] Category Theory woes

Gregg Reynolds wrote:

On Thu, Feb 18, 2010 at 7:48 AM, Nick Rudnick
joerg.rudn...@t-online.de mailto:joerg.rudn...@t-online.de wrote:

IM(H??)O, a really introductive book on category theory still
is to be written -- if category theory is really that
fundamental (what I believe, due to its lifting of
restrictions usually implicit at 'orthodox maths'), than it
should find a reflection in our every day's common sense,
shouldn't it?


Goldblatt works for me.

Accidentially, I have Goldblatt here, although I didn't read it before 
-- you agree with me it's far away from every day's common sense, even 
for a hobby coder?? I mean, this is not «Head first categories», is 
it? ;-)) With «every day's common sense» I did not mean «a 
mathematician's every day's common sense», but that of, e.g., a 
housewife or a child...


But I have became curious now for Goldblatt...

 



* the definition of open/closed sets in topology with the
boundary elements of a closed set to considerable extent
regardable as facing to an «outside» (so that reversing these
terms could even appear more intuitive, or «bordered» instead
of closed and «unbordered» instead of open),


Both have a border, just in different places.

Which elements form the border of an open set??



As an example, let's play a little:

Arrows: Arrows are more fundamental than objects, in fact,
categories may be defined with arrows only. Although I like
the term arrow (more than 'morphism'), I intuitively would
find the term «reference» less contradictive with the actual
intention, as this term

Arrows don't refer. 

A *referrer* (object) refers to a *referee* (object) by a *reference* 
(arrow).


 


Categories: In every day's language, a category is a
completely different thing, without the least


Not necesssarily (for Kantians, Aristoteleans?)

Are you sure...?? See 
http://en.wikipedia.org/wiki/Categories_(Aristotle) ...


  If memory serves, MacLane says somewhere that he and Eilenberg
picked the term category as an explicit play on the same term in
philosophy.

In general I find mathematical terminology well-chosen and
revealing, if one takes the trouble to do a little digging.  If
you want to know what terminological chaos really looks like try
linguistics.

;-) For linguistics, granted... In regard of «a little digging», don't 
you think terminology work takes a great share, especially at 
interdisciplinary efforts? Wouldn't it be great to be able to drop, 
say 20% or even more, of such efforts and be able to progress more 
fluidly ?



-g



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