User talk:JahJah
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[edit] x=0 in domain?
Hi. I see you are a mathematician, so I am a bit abashed, but I did not see you exclude zero from the domain. Did you? Also even if you exclude zero, you would have a jump between the asymptote as x->0 from either side (positive or negative). (i.e. plus infinity and minus infinity). Also, would you be planning that a person would exclude the points +1 and -1 for the rational function 1/(x^2-1) and so on - for each rational function you exclude its real zeros? And maybe for complex cases, too?
I did have Math 212: Functions of a Real Variable (from Richard Dagobert Brower) at Harvard in 1956, and at the same time Functions of a Complex Variable (Math 213) from George Mackey, and got A's, so I feel somewhat qualified. Best regards Pdn 17:36, 18 August 2005 (UTC)
Hi Pdn! I'm glad to see you still have strong memories of your professors.
Normally when we write a function as a formula like 1/x, we mean that its domain is the subset of the real numbers on which it makes sense, namely all nonzero numbers. As well as for rational functions, the same applies to tan, sec, csc, cot, ln, etc. Continuity only involves the values of the function in its domain, even though this means that we lose the intuitive idea of drawing the curve without taking the pencil off the page. This is also why I removed the redundant comment about domains.
What you are thinking (which is true) is that 1/x cannot be extended to a continuous function on R, that is, it does not have a removable singularity. But this is a different question from continuity.--JahJah 17:56, 18 August 2005 (UTC)
OK Pdn 04:09, 19 August 2005 (UTC)
[edit] complicated links
Hello. Please note that you don't need to write [[polynomial|polynomials]], since writing [[polynomial]]s makes the whole word, not just the part in brackets, appear as a clickable link, which links to the article whose title is inside the brackets. Similarly [[logic]]al, [[Russia]]n, [[dogma]]tic, [[hyphen]]ated, [[rabbi]]nical, [[dog]]s, [[apocrypha]]l, etc. The more complicated form can be used for [[geometry|geometries]] and the like. Michael Hardy 21:13, 18 August 2005 (UTC)
- OK, point taken. I think it's a hangover from using LaTeX crossreferences. --JahJah 21:19, 18 August 2005 (UTC)
[edit] continuity
I still disagree with this. If you take the integers with the subspace topology from the reals, they have the discrete topology, and so every function defined on the integers is continuous. Continuity is an intrinsic property: it does not depend on the domain or codomain being included in any other space. This is the definition used for metric spaces (including the reals and subsets thereof) as well as for topological spaces in general. A discontinuity can mean several things, but bringing it into the definition like this is, in my opinion, a mistake in terms of exposition as well as being mathematically inaccurate. --JahJah 21:44, 18 August 2005 (UTC)
- You're not reading carefully, I think. The article did not say, either before or after my rephrasing, that continuity depends on extendability to a continuous function at an accumulation point not in the domain. It said, about a point c that IS IN THE DOMAIN, that if it is an accumulation point, then a certain condition is necessary for continuity. Of course, that condition is still necessary if c is not an accumulation point, but then it holds vacuously, so it's not necessary to include it explicitly in the definition. Michael Hardy 22:10, 18 August 2005 (UTC)
[edit] Wikipedia New York Meet-Up
Howdy! Please come to the First Annual New York Wikipedian Central Park Picnic. R.S.V.P. @ Wikipedia:Meetup/NYC --David Shankbone 14:37, 9 June 2007 (UTC)
[edit] New York City Meetup
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New York City Meetup
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The agenda for the next meetup includes the formation of a Wikimedia New York City local chapter. Hope to see you there! --Pharos 18:59, 19 October 2007 (UTC)
[edit] You're invited!
...to the next New York City Meetup!
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New York City Meetup
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In the morning, there are exciting plans for a behind-the-scenes guided tour of the American Museum of Natural History.
In the afternoon, we will hold a session dedicated to discussing meta:Wikimedia New York City issues (see the last meeting's minutes).
In the evening, we'll share dinner and chat at a local restaurant, and (weather permitting) hold a late-night astronomy event at Columbia's telescopes.
You can add or remove your name from the New York City Meetups invite list at Wikipedia:Meetup/NYC/Invite list.
This has been an automated delivery by BrownBot (talk) 01:07, 5 January 2008 (UTC)
[edit] New mailing list
There has been a mailing list created for Wikipedians in the New York metropolitan area (list: Wikimedia NYC). Please consider joining it! Cbrown1023 talk 21:11, 22 February 2008 (UTC)
[edit] You are invited!
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New York City Meetup
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In the afternoon, we will hold a session dedicated to meta:Wikimedia New York City activities, and have salon-style group discussions on Wikipedia and the other Wikimedia projects (see the last meeting's minutes).
Well also make preparations for our exciting Wikipedia Takes Manhattan event, a free content photography contest for Columbia University students planned for Friday March 28 (about 2 weeks after our meeting).
In the evening, we'll share dinner and chat at a local restaurant, and (weather permitting) hold a late-night astronomy event at Columbia's telescopes.
You can add or remove your name from the New York City Meetups invite list at Wikipedia:Meetup/NYC/Invite list.
You're also invited to subscribe to the public Wikimedia New York City mailing list, which is a great way to receive timely updates.
This has been an automated delivery because you were on the invite list. BrownBot (talk) 02:57, 4 March 2008 (UTC)
[edit] NYC Meetup: June 1, 2008
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New York City Meetup
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In the afternoon, we will hold a session dedicated to meta:Wikimedia New York City activities, elect a board of directors, and hold salon-style group discussions on Wikipedia and the other Wikimedia projects (see the last meeting's minutes).
We'll also review our recent Wikipedia Takes Manhattan event, and make preparations for our exciting successor Wiki Week bonanza, being planned with Columbia University students for September or October.
In the evening, we'll share dinner and chat at a local restaurant, and (weather permitting) hold a late-night astronomy event at Columbia's telescopes.
You can add or remove your name from the New York City Meetups invite list at Wikipedia:Meetup/NYC/Invite list.
Also, check out our regional US Wikimedia chapters blog Wiki Northeast (and we're open to guest posts).
This has been an automated delivery by BrownBot (talk) 23:55, 19 May 2008 (UTC)
