Agreed.   Nobody convinced me that Rosen was ever really doing category 
theory anyhow.  If all you need is the category Set, why mobilize 
algebraic topology?   Leave the hyper-dimensional warp drive in the garage.

Russell Standish wrote:
> The standard language of maps (aka functions) over sets will give you
> want you want. Category theory is not needed.
>
> On Sat, Aug 09, 2008 at 08:58:02PM -0600, Nicholas Thompson wrote:
>   
>> Roseners, and anybody else vaguely interested in category theory.  
>>
>> Rosen seems to be interested in situations in which A maps to B but not all 
>> the values in B can be generated by the mapping.  
>>
>> this is a lot like the Intension and the Extension of an utterance.  I say 
>> with assurance that Mrs. Vanderbilt wished to sail on the Titanic.  In this 
>> case, Mrs Vanderbilt's "wanting" is a function  (mathematical sense) that 
>> maps from her wants to a subset of the properties of the Titanic.  All the 
>> properties of the Titanic constitute (in philosophic lingo ) it's extension. 
>>  The subset, the "image" of Mrs Vanderbilt's wanting , constitutes the 
>> intension of her utterance, "I want to sail on the Titanic."  Among the 
>> titanic's attributes, but outside that image, is the property "hit an 
>> iceberg in the North Atlantic and sank."  
>>
>> I guess the question is whether there is a less tortured mathematics than 
>> category theory that would allow one to talk about these things. 
>>
>> N
>>
>>
>>
>>
>>
>> Nicholas S. Thompson
>> Emeritus Professor of Psychology and Ethology, 
>> Clark University ([EMAIL PROTECTED])
>> ============================================================
>> FRIAM Applied Complexity Group listserv
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>>     
>
>   

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