Re: [Haskell-cafe] Category Theory woes

2010-02-21 Thread Richard O'Keefe
On Feb 21, 2010, at 8:13 AM, Nick Rudnick wrote: Of course a basic point about language is that the association between sounds and meanings is (for the most part) arbitrary. I would rather like to say it is not strictly determined, as an evolutionary tendence towards, say ergonomy, cannot be

Re: [Haskell-cafe] Category Theory woes

2010-02-20 Thread Nick Rudnick
Richard O'Keefe wrote: On Feb 19, 2010, at 2:48 PM, Nick Rudnick wrote: Please tell me the aspect you feel uneasy with, and please give me your opinion, whether (in case of accepting this) you would rather choose to consider Human as referrer and Int as referee of the opposite -- for I think

Re: [Haskell-cafe] Category Theory woes

2010-02-20 Thread Nick Rudnick
A place in the hall of fame and thank you for mentioning clopen... ;-) Just wanting to present open/closed as and example of improvable maths terminology, I oversaw this even more evident defect in it and even copied it into my improvement proposal, bordered/unbordered: It is questionable sty

Re: [Haskell-cafe] Category Theory woes

2010-02-19 Thread Daniel Fischer
Am Freitag 19 Februar 2010 02:48:59 schrieb Nick Rudnick: > Hi, > > wow, a topic specific response, at last... But I wish you would be more > specific... ;-) > > >> A *referrer* (object) refers to a *referee* (object) by a *reference* > >> (arrow). > > > > Doesn't work for me. Not in Ens (sets, map

Re: [Haskell-cafe] Category Theory woes

2010-02-19 Thread Daniel Fischer
Am Freitag 19 Februar 2010 01:49:05 schrieb Nick Rudnick: > Daniel Fischer wrote: > > Am Donnerstag 18 Februar 2010 19:19:36 schrieb Nick Rudnick: > >> Hi Hans, > >> > >> agreed, but, in my eyes, you directly point to the problem: > >> > >> * doesn't this just delegate the problem to the topic of l

Re: [Haskell-cafe] Category Theory woes

2010-02-19 Thread Hans Aberg
On 19 Feb 2010, at 12:12, Daniel Fischer wrote: ...As far as I know, the term "ring" (in the mathematical sense) first appears in chapter 9 - Die Zahlringe des Körpers - of Hilbert's "Die Theorie der algebraischen Zahlkörper". Unfortunately, Hilbert gives no hint why he chose that name (Dedekind

Re: [Haskell-cafe] Category Theory woes

2010-02-19 Thread Daniel Fischer
Am Freitag 19 Februar 2010 10:42:59 schrieb Hans Aberg: > On 19 Feb 2010, at 00:55, Daniel Fischer wrote: > >> I'd always assumed "ring" was generalised from Z[n]. > > > > As in "cyclic group", arrange the numbers in a ring like on a > > clockface? > > Maybe. As far as I know, the term "ring" (in t

Re: [Haskell-cafe] Category Theory woes

2010-02-19 Thread Hans Aberg
On 19 Feb 2010, at 00:55, Daniel Fischer wrote: I'd always assumed "ring" was generalised from Z[n]. As in "cyclic group", arrange the numbers in a ring like on a clockface? Maybe. As far as I know, the term "ring" (in the mathematical sense) first appears in chapter 9 - Die Zahlringe des

Re: [Haskell-cafe] Category Theory woes

2010-02-19 Thread Hans Aberg
On 19 Feb 2010, at 00:05, Nick Rudnick wrote: Mathematicians though stick to their own concepts and definitions individually. For example, I had conversations with one who calls monads "triads", and then one has to cope with that. Yes. But isn't it also an enrichment by some way? Yes, one

Re: [Haskell-cafe] Category Theory woes

2010-02-19 Thread Hans Aberg
On 19 Feb 2010, at 00:52, Richard O'Keefe wrote: Turning to the Wikipedia article, we find "The word kangaroo derives from the Guugu Yimidhirr word gangurru, referring to a grey kangaroo" Thanks, particularly for giving the name of the native language. Hope the Wikipedia article can be trust

Re: [Haskell-cafe] Category Theory woes

2010-02-18 Thread Richard O'Keefe
On Feb 19, 2010, at 2:48 PM, Nick Rudnick wrote: Please tell me the aspect you feel uneasy with, and please give me your opinion, whether (in case of accepting this) you would rather choose to consider Human as referrer and Int as referee of the opposite -- for I think this is a deep questi

Re: [Haskell-cafe] Category Theory woes

2010-02-18 Thread Nick Rudnick
Hi, wow, a topic specific response, at last... But I wish you would be more specific... ;-) A *referrer* (object) refers to a *referee* (object) by a *reference* (arrow). Doesn't work for me. Not in Ens (sets, maps), Grp (groups, homomorphisms), Top (topological spaces, continuous map

Re: [Haskell-cafe] Category Theory woes

2010-02-18 Thread Nick Rudnick
Hi Alexander, please be more specific -- what is your proposal? Seems as if you had more to say... Nick Alexander Solla wrote: On Feb 18, 2010, at 4:49 PM, Nick Rudnick wrote: Why does the opposite work well for computing science? Does it? I remember a peer trying to convince me to u

Re: [Haskell-cafe] Category Theory woes

2010-02-18 Thread Alexander Solla
On Feb 18, 2010, at 4:49 PM, Nick Rudnick wrote: Why does the opposite work well for computing science? Does it? I remember a peer trying to convince me to use "the factory pattern" in a language that supports functors. I told him I would do my task my way, and he could change it later

Re: [Haskell-cafe] Category Theory woes

2010-02-18 Thread Nick Rudnick
Daniel Fischer wrote: Am Donnerstag 18 Februar 2010 19:19:36 schrieb Nick Rudnick: Hi Hans, agreed, but, in my eyes, you directly point to the problem: * doesn't this just delegate the problem to the topic of limit operations, i.e., in how far is the term «closed» here more perspicuous?

Re: [Haskell-cafe] Category Theory woes

2010-02-18 Thread Daniel Fischer
Am Freitag 19 Februar 2010 00:24:23 schrieb Richard O'Keefe: > On Feb 19, 2010, at 3:55 AM, Daniel Fischer wrote: > > Am Donnerstag 18 Februar 2010 14:48:08 schrieb Nick Rudnick: > >> even in Germany, where the > >> term «ring» seems to originate from, since at least a century nowbody > >> has the

Re: [Haskell-cafe] Category Theory woes

2010-02-18 Thread Richard O'Keefe
On Feb 19, 2010, at 11:22 AM, Hans Aberg wrote: As for the naming problem, it is more of a linguistic problem: the names were somehow handed by tradition, and it may be difficult to change them. For example, there is a rumor that "kangaroo" means "I do not understand" in a native language;

Re: [Haskell-cafe] Category Theory woes

2010-02-18 Thread Nick Rudnick
Alexander Solla wrote: On Feb 18, 2010, at 2:08 PM, Nick Rudnick wrote: my actual posting was about rename refactoring category theory; closed/open was just presented as an example for suboptimal terminology in maths. But of course, bordered/unbordered would be extended by e.g. «partially bo

Re: [Haskell-cafe] Category Theory woes

2010-02-18 Thread Richard O'Keefe
On Feb 19, 2010, at 3:55 AM, Daniel Fischer wrote: Am Donnerstag 18 Februar 2010 14:48:08 schrieb Nick Rudnick: even in Germany, where the term «ring» seems to originate from, since at least a century nowbody has the least idea it once had an alternative meaning «gang,band,group», Wrong. T

Re: [Haskell-cafe] Category Theory woes

2010-02-18 Thread Nick Rudnick
Hans Aberg wrote: On 18 Feb 2010, at 23:02, Nick Rudnick wrote: 418 bytes in my file system... how many in my brain...? Is it efficient, inevitable? Yes, it is efficient conceptually. The idea of closed sets let to topology, and in combination with abstractions of differential geometry led

Re: [Haskell-cafe] Category Theory woes

2010-02-18 Thread Michael Matsko
4:03 PM GMT -05:00 US/Canada Eastern Subject: Re: [Haskell-cafe] Category Theory woes Hi Mike, of course... But in the same spirit, one could introduce a straightforward extension, «partially bordered», which would be as least as good as «clopen»... ;-) I must admit we've come a li

Re: [Haskell-cafe] Category Theory woes

2010-02-18 Thread Alexander Solla
On Feb 18, 2010, at 2:08 PM, Nick Rudnick wrote: my actual posting was about rename refactoring category theory; closed/open was just presented as an example for suboptimal terminology in maths. But of course, bordered/unbordered would be extended by e.g. «partially bordered» and the same

Re: [Haskell-cafe] Category Theory woes

2010-02-18 Thread Nick Rudnick
Gregg Reynolds wrote: On Thu, Feb 18, 2010 at 1:31 PM, Daniel Fischer mailto:daniel.is.fisc...@web.de>> wrote: Am Donnerstag 18 Februar 2010 19:55:31 schrieb Nick Rudnick: > Gregg Reynolds wrote: > -- you agree with me it's far away from every day's common sense, even >

Re: [Haskell-cafe] Category Theory woes

2010-02-18 Thread Hans Aberg
On 18 Feb 2010, at 23:02, Nick Rudnick wrote: 418 bytes in my file system... how many in my brain...? Is it efficient, inevitable? Yes, it is efficient conceptually. The idea of closed sets let to topology, and in combination with abstractions of differential geometry led to cohomology th

Re: [Haskell-cafe] Category Theory woes

2010-02-18 Thread Nick Rudnick
Hi Alexander, my actual posting was about rename refactoring category theory; closed/open was just presented as an example for suboptimal terminology in maths. But of course, bordered/unbordered would be extended by e.g. «partially bordered» and the same holds. Cheers, Nick Alexander So

Re: [Haskell-cafe] Category Theory woes

2010-02-18 Thread Nick Rudnick
Hans Aberg wrote: On 18 Feb 2010, at 19:19, Nick Rudnick wrote: agreed, but, in my eyes, you directly point to the problem: * doesn't this just delegate the problem to the topic of limit operations, i.e., in how far is the term «closed» here more perspicuous? * that's (for a very simple con

Re: [Haskell-cafe] Category Theory woes

2010-02-18 Thread Alexander Solla
On Feb 18, 2010, at 1:28 PM, Hans Aberg wrote: It is a powerful concept. I think of a function closure as what one gets when adding all an expression binds to, though I'm not sure that is why it is called a closure. Its because a monadic morphism into the same type carrying around data i

Re: [Haskell-cafe] Category Theory woes

2010-02-18 Thread Nick Rudnick
7;t it? Cheers, Nick Michael Matsko wrote: - Forwarded Message - From: "Michael Matsko" To: "Nick Rudnick" Sent: Thursday, February 18, 2010 2:16:18 PM GMT -05:00 US/Canada Eastern Subject: Re: [Haskell-cafe] Category Theory woes Gregg

Re: [Haskell-cafe] Category Theory woes

2010-02-18 Thread Hans Aberg
On 18 Feb 2010, at 22:06, Daniel Fischer wrote: ...missing are - c(x) contains x - c(x) is minimal among the sets containing x with y = c(y). It suffices*) with a lattice L with relation <= (inclusion in the case of sets) satifying i. x <= y implies c(x) <= c(y) ii. x <= c(x) for all x i

Re: [Haskell-cafe] Category Theory woes

2010-02-18 Thread Michael Matsko
set does, doesn't it? Cheers,     Nick Michael Matsko wrote: - Forwarded Message - From: "Michael Matsko" To: "Nick Rudnick" Sent: Thursday, February 18, 2010 2:16:18 PM GMT -05:00 US/Canada Eastern Subject: Re: [Haskell-cafe] Category Theory woes Gre

Re: [Haskell-cafe] Category Theory woes

2010-02-18 Thread Gregg Reynolds
On Thu, Feb 18, 2010 at 1:31 PM, Daniel Fischer wrote: > Am Donnerstag 18 Februar 2010 19:55:31 schrieb Nick Rudnick: > > Gregg Reynolds wrote: > > > -- 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?

Re: [Haskell-cafe] Category Theory woes

2010-02-18 Thread Daniel Fischer
Am Donnerstag 18 Februar 2010 21:47:02 schrieb Hans Aberg: > On 18 Feb 2010, at 20:20, Daniel Fischer wrote: > >> + definition backtracking: «A closure operation c is defined by the > >> property c(c(x)) = c(x). > > > > Actually, that's incomplete, ... > > That's right, it is just the idempotency r

Re: [Haskell-cafe] Category Theory woes

2010-02-18 Thread Hans Aberg
On 18 Feb 2010, at 19:19, Nick Rudnick wrote: agreed, but, in my eyes, you directly point to the problem: * doesn't this just delegate the problem to the topic of limit operations, i.e., in how far is the term «closed» here more perspicuous? * that's (for a very simple concept) the way th

Re: [Haskell-cafe] Category Theory woes

2010-02-18 Thread Hans Aberg
On 18 Feb 2010, at 20:20, Daniel Fischer wrote: + definition backtracking: «A closure operation c is defined by the property c(c(x)) = c(x). Actually, that's incomplete, ... That's right, it is just the idempotency relation. ...missing are - c(x) contains x - c(x) is minimal among the sets

Re: [Haskell-cafe] Category Theory woes

2010-02-18 Thread Alexander Solla
On Feb 18, 2010, at 10:19 AM, Nick Rudnick wrote: Back to the case of open/closed, given we have an idea about sets -- we in most cases are able to derive the concept of two disjunct sets facing each other ourselves, don't we? The only lore missing is just a Bool: Which term fits which ide

Re: [Haskell-cafe] Category Theory woes

2010-02-18 Thread Daniel Fischer
Am Donnerstag 18 Februar 2010 19:55:31 schrieb Nick Rudnick: > Gregg Reynolds wrote: > > On Thu, Feb 18, 2010 at 7:48 AM, Nick Rudnick > > mailto:joerg.rudn...@t-online.de>> wrote: > > > > IM(H??)O, a really introductive book on category theory still is > > to be written -- if category theo

Re: [Haskell-cafe] Category Theory woes

2010-02-18 Thread Daniel Fischer
Am Donnerstag 18 Februar 2010 19:19:36 schrieb Nick Rudnick: > Hi Hans, > > agreed, but, in my eyes, you directly point to the problem: > > * doesn't this just delegate the problem to the topic of limit > operations, i.e., in how far is the term «closed» here more perspicuous? It's fairly natural

Re: [Haskell-cafe] Category Theory woes

2010-02-18 Thread Nick Rudnick
Gregg Reynolds wrote: On Thu, Feb 18, 2010 at 7:48 AM, Nick Rudnick 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 restri

Re: [Haskell-cafe] Category Theory woes

2010-02-18 Thread Nick Rudnick
Hi Hans, agreed, but, in my eyes, you directly point to the problem: * doesn't this just delegate the problem to the topic of limit operations, i.e., in how far is the term «closed» here more perspicuous? * that's (for a very simple concept) the way that maths prescribes: + historical backgro

Re: [Haskell-cafe] Category Theory woes

2010-02-18 Thread Gregg Reynolds
On Thu, Feb 18, 2010 at 7:48 AM, Nick Rudnick 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 fi

Re: [Haskell-cafe] Category Theory woes

2010-02-18 Thread Daniel Fischer
Am Donnerstag 18 Februar 2010 17:10:08 schrieb Nick Rudnick: > Hi Daniel, > > ;-)) agreed, but is the word «Ring» itself in use? Of course, many people wear rings on their fingers. Oh - you meant "in the sense of gang/group"? It still appears as part of the name of some groups as a word of its o

Re: [Haskell-cafe] Category Theory woes

2010-02-18 Thread Nick Rudnick
Hi Daniel, ;-)) agreed, but is the word «Ring» itself in use? The same about the English language... de.wikipedia says: « Die Namensgebung /Ring/ bezieht sich nicht auf etwas anschaulich Ringförmiges, sondern auf einen organisierten Zusammenschluss von Elementen zu einem Ganzen. Diese Wortb

Re: [Haskell-cafe] Category Theory woes

2010-02-18 Thread Daniel Fischer
Am Donnerstag 18 Februar 2010 14:48:08 schrieb Nick Rudnick: > even in Germany, where the > term «ring» seems to originate from, since at least a century nowbody > has the least idea it once had an alternative meaning «gang,band,group», Wrong. The term "Ring" is still in use with that meaning in c

Re: [Haskell-cafe] Category Theory woes

2010-02-18 Thread Hans Aberg
On 18 Feb 2010, at 14:48, Nick Rudnick wrote: * 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 clo

Re: [Haskell-cafe] Category Theory woes

2010-02-18 Thread Nick Rudnick
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

Re: [Haskell-cafe] Category Theory woes

2010-02-18 Thread Sean Leather
On Thu, Feb 18, 2010 at 04:27, Nick Rudnick wrote: > I haven't seen anybody mentioning «Joy of Cats» by Adámek, Herrlich & > Strecker: > > It is available online, and is very well-equipped with thorough > explanations, examples, exercises & funny illustrations, I would say best of > university le

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

2010-02-18 Thread Mike Pentney
As well as books and reading material online, nowadays you can also find video lectures...for example, the following was at the top of Googling "category theory video": http://golem.ph.utexas.edu/category/2007/09/the_catsters_on_youtube.html Cheers, Mike. Nick Rudnick wrote: I haven't seen a

Re: [Haskell-cafe] Category Theory woes

2010-02-17 Thread Nick Rudnick
I haven't seen anybody mentioning «Joy of Cats» by Adámek, Herrlich & Strecker: It is available online, and is very well-equipped with thorough explanations, examples, exercises & funny illustrations, I would say best of university lecture style: http://katmat.math.uni-bremen.de/acc/. (Actua

Re: [Haskell-cafe] Category Theory woes

2010-02-16 Thread Alexander Solla
On Feb 16, 2010, at 9:43 AM, Gregg Reynolds wrote: I've looked through at least a dozen. For neophytes, the best of the bunch BY FAR is Goldblatt, Topoi: the categorial analysis of logic . Don't be put off by the title. He not only explains the stuff, but he explains the problems that mo

Re: [Haskell-cafe] Category Theory woes

2010-02-16 Thread Gregg Reynolds
On Tue, Feb 2, 2010 at 5:26 AM, Mark Spezzano wrote: > Hi all, > > Has anyone else found it frustratingly difficult to find details on > easy-to-diget material on Category theory. The Chapter that I'm stuck on is > actually labeled Preliminaries and so I reason that if I can't > I've looked throu

Re: [Haskell-cafe] Category Theory woes

2010-02-02 Thread Creighton Hogg
2010/2/2 Álvaro García Pérez > You may try Pierce's "Basic Category Theory for Computer Scientists" or > Awodey's "Category Theory", whose style is rather introductory. Both of them > (I think) have a chapter about functors where they explain the Hom functor > and related topics. > I think Awode

Re: [Haskell-cafe] Category Theory woes

2010-02-02 Thread A E Lawrence
Mark Spezzano wrote: I need a text for a newbie. While the other books suggested are excellent, I think that they would be hard going if you find Barr & Wells difficult. The simplest introduction to the ideas of category theory that I know is "Conceptual Mathematics" by F W Lawvere & S H Sc

Re: [Haskell-cafe] Category Theory woes

2010-02-02 Thread Álvaro García Pérez
You may try Pierce's "Basic Category Theory for Computer Scientists" or Awodey's "Category Theory", whose style is rather introductory. Both of them (I think) have a chapter about functors where they explain the Hom functor and related topics. Alvaro. 2010/2/2 Mark Spezzano > I should probably

Re: [Haskell-cafe] Category Theory woes

2010-02-02 Thread Miguel Mitrofanov
Hom(A, B) is just a set of morphisms from A to B. Mark Spezzano wrote: I should probably add that I am trying various proofs that involve injective and surjective properties of Hom Sets and Hom functions. Does anyone know what Hom stands for? I need a text for a newbie. Mark On 02/02/2010,

Re: [Haskell-cafe] Category Theory woes

2010-02-02 Thread Mark Spezzano
I should probably add that I am trying various proofs that involve injective and surjective properties of Hom Sets and Hom functions. Does anyone know what Hom stands for? I need a text for a newbie. Mark On 02/02/2010, at 9:56 PM, Mark Spezzano wrote: > Hi all, > > I'm trying to learn Haske