User talk:Trieu

Welcome!

Hello, Trieu, and welcome to Wikipedia! Thank you for your contributions. I hope you like the place and decide to stay. Here are a few good links for newcomers:

I hope you enjoy editing here and being a Wikipedian! Please sign your name on talk pages using four tildes (~~~~); this will automatically produce your name and the date. If you need help, check out Wikipedia:Where to ask a question, ask me on my talk page, or place {{helpme}} on your talk page and someone will show up shortly to answer your questions. Again, welcome! SWAdair | Talk 09:45, 14 Dec 2004 (UTC)

Namespace

Hello. You have been creating an encyclopedia article with your name, stating that you intend to place your opened projects there. Your user page is where you can place information about yourself and projects your'e working on, but the article space is for articles. If you would like to create a subpage of your userspace, all you have to do is add a slash and the subpage name. For instance, User_talk:Trieu/Projects. Thank you. SWAdair | Talk 09:45, 14 Dec 2004 (UTC)

English language

Hi, Trieu. Your English is excellent, but sometimes we all need a little help. Deb 17:26, 27 Mar 2005 (UTC)

Dual Space

Hi Lethe, my name is Trieu. I had made some minor changes at Dual space. I added a small example and exchange locations between "covariance" and "contravariance". Am I correct? Could you please help me to modify them if my previous modification is wrong.

Thanks. Trieu

I see that you switched the words covariant and contravariant. Here is what I can say about this: physicists doing relativity call things that transform like coordinates contravariant vectors, and things that transform like derivatives with respect to coordinates covariant vectors. This is confusing, because things that transorm like coordinates are components of sections of the tangent bundle (and so might be called covariant), while things which transform like derivatives are components of sections of the dual of the tangent bundle, the cotangent bundle (and so might be called contravariant). Some authors respond to this unfortunate situation by switching the usage of the words, while others agree to stop using the words altogether in the context of tangent and cotangent vectors. -Lethe | Talk 21:55, 6 November 2005 (UTC)[reply]