[Haskell-cafe] Re: category theory tutorial pdfs .....

Benjamin L.Russell DekuDekuplex at Yahoo.com
Fri Aug 1 08:44:08 EDT 2008

On Fri, 1 Aug 2008 00:52:41 -0500, "Galchin, Vasili"
<vigalchin at gmail.com> wrote:

>    Prof. Harold Simmons' tutorial IMO are like a Russian matroshka doll ...
>first layer is for newbie ... inner layers require more sophistication. IMO
>a very subtle writer ... I have every book imaginable on cat theory and
>topos theory so I think can compare a little.
>       1) http://www.cs.man.ac.uk/~hsimmons/BOOKS/books.html  ... an earlier
>version ... "An Intro to Category Theory in Four Easy Movements" ... this
>version delves a little into Topos Theory ... pretty subtle .. cool

I have started reading _An introduction to category theory in four
easy movements_ (see
http://www.cs.man.ac.uk/~hsimmons/BOOKS/CatTheory.pdf).  The author's
style is very strange; in the first section, he states that he
highlights "subsidiary notions" to be defined later in small caps, and
even uses some of these in his exercises.  For example, he highlights
and uses "preset" and "monoid" as part of Exercise 1.1 before defining
them, so I then need to hunt around in the vicinity for definitions
(available several pages later).  However, the PDF file is not
text-searchable, so I need to hunt manually through the vicinity of
pages to find a definition.

This makes the book more interesting, at the expense of being harder
to use.  Do you know of a text-searchable version of this file?

He also has a rather peculiar sense of humor.  For instance, on page
6, he writes (regarding that in the original examples of categories,
"the arrows were morphisms which were then called homomorphism, and it
wasn't realized that this family could be very large"), 

> (Some out and out category theorists still don't realize the significance of this.  
> On the other hand, some off the wall set theorists don't realize the significance 
> of category theory.)

This reminds me of a lecture by David Gelernter in 1992 in a survey
course on cognitive science at Yale in which he said that some weak AI
cognitive scientists had said that other strong AI cognitive
scientists must have been "out to lunch."

Again, if you know of a text-searchable version of this book, please
post the reference in this thread.

-- Benjamin L. Russell

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