User talk:Charles Matthews/Archive 5

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Archive 4 Archive 5 Archive 6

Small World indeed

I am sitting on St Andrew's St just back from a holiday in Southwold and we've met before on the maths pages. So small world indeed. In fact I think I remember you from a long time back (I did ba/phd/fellowship in maths here) but I could be mistaken. BTW you're right to move small presses to a separate page it will be a long list --BozMo|talk 09:43, 20 Sep 2004 (UTC)

With any luck, we'll meet at the go club ... Charles Matthews 09:45, 20 Sep 2004 (UTC)

Hope so but evenings are tricky (I live a bit out and have tiny kids). I was hoping for some lunchtime thing but I'll try. I haven't played for 23 years though. :o)

Sunday afternoon at CB1 starts at around 4 pm and quite informal. Charles Matthews 09:50, 20 Sep 2004 (UTC)

Wikipedia:UK Wikipedians' notice board

Hi Charles how are you? User:Francs2000 has created the above page and invited a number of british people to join. I can't see an invitation to you on your talk page so just in case he missed you out, I'd like to formally invite you to join (or at least add it to your watchlist) Theresa Knott (The torn steak) 10:09, 4 Oct 2004 (UTC)

Thanks - and not a moment too soon to get everything much more organised. Charles Matthews 10:13, 4 Oct 2004 (UTC)

"First-year calculus"

rm 'first-year' - US-centric (in the UK 17 year olds)

In the USA it's also 17-year-olds, in the last year of secondary school. But it's still the first year of calculus. (A course involving div, grad, curl, jacobians, differential equations, etc., is often called 2nd-year calculus. A course after that using Baby Rudin (i.e., his Principles of Mathematical Analysis) or books at a similar level but differently focused, is sometimes called advanced calculus.) Of course, many students who do not go into fields relying on mathematics learn calculus later, sometimes much later. Michael Hardy 19:46, 6 Oct 2004 (UTC)

Well, that's still fairly indefinite, and depends on how calculus is introduced; plenty of sixteen-year-olds here have already seen some differential calculus, and certainly the way of teaching can mix it up with mechanics. Anyway the point is that the particular case submits to 'techniques of integration'.

Charles Matthews 19:53, 6 Oct 2004 (UTC)

On this side of the Pond, "11th grade" is typically entered by 16-year-olds who finish when they're 17 and then begin 12th grade. In 11th grade, it is not unusual to to learn differentiation of polynomial functions and summation of some infinite series. The full-scale calculus course is done in 12th grade. Except that those are not courses that are required of all pupils. Some of course take only as much math as is required of everyone. Those don't learn the algebra prerequisites to calculus unless they go on to colleges or universities that require them, and sometimes they postpone them as long as possible because they hate math and then find that they can't graduate without just one more course, a math course they would have had in 10th grade if they'd taken the opposite approach to learning math. Michael Hardy 22:24, 6 Oct 2004 (UTC)

The strange thing is that I have actually taught calculus only in the USA Charles Matthews 05:38, 7 Oct 2004 (UTC)

Conditional expectation

I have to say - the 'intuitive' explanation always went right by me. Charles Matthews 21:15, 8 Oct 2004 (UTC)

OK, here's something from another Wikipedia article:

The conditional expected value E( X | Y ) is a random variable in its own right, whose value depends on the value of Y. Notice that the conditional expected value of X given the event Y = y is a function of y (this is where adherence to the conventional rigidly case-sensitive notation of probability theory becomes important!). If we write E( X | Y = y) = g(y) then the random variable E( X | Y ) is just g(Y). Similar comments apply to the conditional variance.

Charles, is that the intuitive explanation that went by you? Michael Hardy 00:02, 9 Oct 2004 (UTC)

Well, I actually meant historically, which must mean thirty years ago now. I put something in the article about the projection interpretation, because I had found it easier to think about, when I came across it. Charles Matthews 07:10, 9 Oct 2004 (UTC)


I noticed that you opposed my RfA without comment, and have been wondering if there is some specific area of concern, or some matters I might clear up in order to have a better impression in your eyes. I understand that I am not going to win the current vote, but frankly that doesn't make the opinions any less important, and I'd like an opportunity to improve your estimation of me, or at least to be able to reflect upon your reasoning. Thanks, Sam [Spade] 16:43, 10 Oct 2004 (UTC)

Well, frankly, I think people can be useful Wikipedians without being sensible, at the level being an admin requires; and that you may fall into that category. Nothing personal - you did ask. Charles Matthews 17:01, 10 Oct 2004 (UTC)

Not at all, indeed that is pretty close to the best reason for opposing me which I can think of. Is there anything in particular which you think shows me to be less than sensible, or any question you would like answered sensibly? I of course think of myself as sensible, but that might be a bit POV? ;) Sam [Spade] 17:06, 10 Oct 2004 (UTC)

I don't really have a comment on that. Perceptions change, when they're not prejudices; and perhaps you should just shrug, and wonder about a nomination at a future time. Charles Matthews 18:01, 10 Oct 2004 (UTC)

OK, cool, thanx. Sam [Spade] 17:52, 11 Oct 2004 (UTC)


Saw you were fixing up the Mark Steyn entry, among other interesting topics... not that I have anything else to say about it, just commenting.... H'm h'm.... well, Mr. Steyn's great.

Also: "I've also met Paul Erdös, Richard Borcherds and Ross Anderson over the board." Apparently Erdös was responsible for this quote: "A mathematician is a machine for turning coffee into theorems."

Anyway, just dropping by... sorry I'm not logged in, I'm away from home (and I forget what my username is), but glad to see somebody writing up Mark Steyn and Lorenz curves etc.

-- 11:27, 13 Oct 2004 (UTC)

Well, hi anyway. I'm not a fan of Steyn, but it's on my watchlist and the garden should be weeded. Yes, I played Erdös twice (I'm better at go, not at mathematics though). Charles Matthews 11:29, 13 Oct 2004 (UTC)

Heh, I made a false assumption I guess, but yes il faut cultiver notre jardin. And, glad to hear you can beat Erdös at go... I've never played, but isn't it vastly more "complex" (i.e. combinations) than chess? if so I'd guess it's at least an approximation of a measure of mathematical intuition (plus visualization), though as you say, of course not mathematics itself. Anyway, getting longwinded, so I'm sorry you don't appreciate Mark Steyn, it's nice to hear (read) your story, and I'm suitably impressed -- that's all. (P.S. I'm exhausted so sorry if this isn't cogent)
-- 11:44, 13 Oct 2004 (UTC)

Erdös told me he could do the tactics, because it was combinatorics, but not the strategy; that was just about true (he was about 2 kyu - go ranks and ratings). It's not that much to do with higher mathematics (you sometimes have to be able to count). Charles Matthews 12:46, 13 Oct 2004 (UTC)

Hi Charles, I noticed you had done some work on Generalized orthogonal group. Some of my colleagues use O(p+q,q) for what is O(p,q) in this article. Do you think this notational difference is widespread enough to be worth mentioning? I have n't found a deffinative reference Billlion 13:40, 13 Oct 2004 (UTC)

There is no universal convention (and none for the signature of a quadratic form). But I'm sure O(p,q) is the right choice, so that the Lorentz group is (3,1) rather than anything else. Charles Matthews 13:44, 13 Oct 2004 (UTC)

Cleaver Disappointment?

I just argued on Wikipedia:Votes for deletion/Cleaver for

  • Keep, for the sense, re glacier-bearing mountains in at least western N. Amer, of a rock formation flanked by two glaciers. (Even if the term is geographically restricted, it would be either a redir to the dominant term, or the target of the redirects from all the other regional terms.) These are important features in mountaineers' planning of ascent and traverse routes, and IMO an article could discuss what they have in common, probably different categories of them, and examples that affect notable routes.

But i count 4 Del to my 1 Keep, and 14 hours left.
--Jerzy(t) 10:43, 2004 Oct 18 (UTC)

Is this a big deal? If cleaver becomes wiktionary-fodder and later someone wants to create cleaver rock formation, has that been prejudiced?

Charles Matthews 14:24, 18 Oct 2004 (UTC)