User talk:Hennobrandsma

Welcome to Wikipedia!
Hello, welcome to Wikipedia!

I saw your work on Sorgenfrey plane and Separable space, and although that's all greek to me, it looks like you know what you're up to. Here's some useful links to places other than article space that you might find useful. If I'm teaching grandma to suck eggs, please forgive.


 * Take a look at the Simplified Ruleset.
 * Read the Tutorial, How to edit a page and the Manual of Style.
 * Find out how to revert, move and merge pages.
 * Sign your posts on talk pages using four tildes (&#126;&#126;&#126;&#126;).
 * Add yourself to the New user log and a regional notice board
 * Ask questions at the Village pump or Help desk.
 * Use the Show preview button
 * Provide an Edit summary
 * Add the correct image copyright tag to any images you upload
 * Take a look at Consensus of standards
 * Create a User page
 * Be bold
 * Ignore all rules

If, for some reason, you are unable to fix a problem yourself, feel free to ask someone else to do it. Wikipedia has a vibrant community of contributors who have a wide range of skills and specialties, and many of them would be glad to help. As well as the wiki community pages there are IRC Channels, where you are more than welcome to ask for assistance. Alf 20:04, 30 August 2005 (UTC)

Collectionwise normal
I came across the article on collectionwise normal spaces that you created. Thanks, and also for the other articles you created. Seeing that you became more active recently, I thought that you could use some advice to save you typing. If you need some advice related to maths on Wikipedia, your best bet is probably to look at WikiProject Mathematics (WikiProject is our jargon for a group of editors working on some subject). I don't know that much topology beyond the basics, but other editors do. Have a look at the list of participants and add yourself if you feel like it. If you have any questions, please feel free to ask me on my talk page (which is at User talk:Jitse Niesen).
 * It's not necessary to type underscores instead of spaces in links. So, instead of , you can simply write.
 * Even better, you can abbreviate  as   ; the software will guess correctly what you mean!

Best wishes, Jitse Niesen (talk) 13:08, 26 February 2007 (UTC)

Mathematics CotW
Hey Henno, I am writing you to let you know that the Mathematics Collaboration of the week(soon to "of the month") is getting an overhaul of sorts and I would encourage you to participate in whatever way you can, i.e. nominate an article, contribute to an article, or sign up to be part of the project. Any help would be greatly appreciated, thanks--Cronholm144 21:38, 13 May 2007 (UTC)

topological characterization of Q
Hi Hennobrandsma,

in "rational number" you wrote that all countable metrizable spaces without isolated points are homeomorphic. Can you give me a reference for this?

Thanks in advance! Stwitzel 10:28, 11 July 2007 (UTC)

Sure, see

for a reference on Topology Atlas