
#19
Nov1410, 07:09 PM

Mentor
P: 16,703

Alright, I've watched everything upto directed sets.
Some remarks:  in video 21 at 51seconds, you say that the cardinality of N is at least the cardinality of B(x). Is this correct? I'm not a native english speaker, but I found that wierd... Also, I kind of missed a counterexample of a directed set. But then again, it's not really vital... It would be nice if you would talk about the specialization preorder sometimes. This is a really handy concept in algebraic geometry, so it would be nice to see a video about it, or just to see it mentioned... Did you make a longterm planning for the video series? I'm quite interested in that 



#20
Nov1710, 09:13 PM

P: 8

Hello there. Sorry about the lack of updates but I've had the combination of not having a job, being very ill and moving home in the last week. I should be able to pump out videos starting early next week. I also want to make sure I introduce nets perfectly, and make sure that all my definitions of limit/adherence in terms of neighbourhoods are perfectly sound and understandable.
Also yeah, that countability thing does sound a little strange, oh well, I hope most people watching will have some set theory understanding anyway. 



#21
Nov2510, 02:28 AM

P: 1

These are awesome! Just so you know I'm a first year undergraduate student and I can understand you PERFECTLY! Except for the bits about countability which I've never seen before but I think I get the idea. A countable set is just one that you can write as a sequence right?




#22
Nov3010, 10:09 AM

Sci Advisor
HW Helper
PF Gold
P: 4,768

Very well done. I'm sure many an undergrad is grateful to you for these clear, concise and colorful explanations.
(CoolPro: You're right that a set is called countable if it can be written as a sequence. But when talking about topological spaces, the word countability usually refers to a property of the topology. There various type of countability properties a topological space can have, and these are generally referred to as "the countability axioms". A given topological space may satisfy some of these axioms or none. You can surely find out what these are on wikipedia.) 



#23
Feb711, 09:13 AM

P: 1

Hello all, after a few months of personal problems I can finally revive and hopefully complete this series. I have two new videos out with more on the way. Thanks to everybody for their support in the past, I have a new determination to see this through.
I'm still open to suggestions on how best to introduce closure, which will likely be in a couple of videos time. http://www.youtube.com/user/ThoughtSpaceZero 



#24
Feb711, 05:13 PM

Mentor
P: 16,703

Ah nice, I quite missed your videos I really like the videos about nets by the way!
How do you best introduce closure? Hmm, that's not easy. There are three ways to do so:  the set of all points of closure  the smallest closed sets containing the original set  the set of all convergence points of nets I think the easiest way is the second. But the first way is more often used... 



#25
Apr112, 09:42 AM

P: 1

What happened to these?



Register to reply 
Related Discussions  
Renate Loll video lectures on quantum gravity (Perimeter Scholars series)  Beyond the Standard Model  12  
What's the difference between differential topology and algebraic topology?  Differential Geometry  5  
K topology strictly finer than standard topology  Calculus & Beyond Homework  5  
Aerospace Video Lecture Series  Aerospace Engineering  1  
Video Requests, Do These Video Tutorials Exist?  Math & Science Learning Materials  2 