Thanks for that link; we should be able to adapt it.

The teaching plan consists of 1.5 hours of classes and 1.5 hours of practicals, and if at all we decide to teach more Python, the stress would be on doing a lot of hands-on stuff.

Couple of things: Irrespective of whether P = NP or not, there exists polynomial-time reductions from any problem in P to any NP-complete problem. I guess you meant it the other way round.

I am not sure in what sense you use the term "undecidable", but if (as it seems likely) you used it to mean independent , then your argument fails at steps 2 and 3.

A proof that P =? NP is undecidable has to only show that one can neither prove nor disprove this statement: it need not show that no polynomial-time reduction exists from from any NP-complete problem to any problem in P.

In other words, undecidable != false.

"symantic" doesn't mean what you think it means.

Chris, Thank you. Zerofree is new to me. I think I will just move my /home and other data partitions out to a spare hard disk after formatting the latter to ext4, and restore these when I get the system back. And for the malware stuff, I guess I will just learn to be less paranoid! Thanks!

No wonder I didn't find it -- this has nothing much to do with my problem.

No, could you?

punit_r, Thanks for your suggestions.

I am not really worried that someone may try really hard to get at the data. I am more concerned about people being curious and just taking a peek in because they can, or trying to log in to some place using stored passwords which they can easily find (open Firefox and try gmail.com, for example).

This is not an option: I don't want to mess up with the laptop and void its warranty.

Thanks! I had been thinking of using cp -ar /home/yourname /media/1TB/backup , but this is much better. And thanks for the warning about ext3 -- I would not have thought about that part at all!

While this does look like it will do the job, I am looking for something not as drastic, or some software that will do this (or something quite similar) for me.

https://www.pwdhash.com/

Available in three ways:

1. Online at the above address -- works with any browser that supports JavaScript.
2. As a plugin for FireFox (and beta plugins for other browsers): Press F2 or type @@ at the beginning of a text field for the plugin to kick in.
3. As a webpage (the one at https://www.pwdhash.com/ )with JavaScript code that you can store on disk and open in any browser.

Constructs a one-way hash of

1. the password entered in a password (or other text) field, and
2. the domain name of the site where the password is used (both these can be entered manually in methods 1 and 3)

to get a domain-specific password. Memorize one strong password and use this utility to get distinct passwords for each domain. The generated passwords are (usually) complicated enough to pass any conceivable non-triviality test.

And what prevents you from inventing this capability for all of us, so that we are no longer disappointed? Just like the way you solved the streaming problem in the first place? Oh wait...

Why don't they just do away with the inefficient step of compiling it twice?

http://www.getdropbox.com/ Works perfectly for me. I use the free option, which has a 2 GB limit, which is more than enough for me to keep all my important stuff in sync. It has a client that integrates nicely with the Nautilus file browser on Ubuntu, which is what I use at home and office. Whatever you put (or symlink) into a designated folder (which you can choose) gets mirrored to their server, from where it gets synced to every other system where you have installed the client, the next time you connect that system to the internet. They also give web-based access to the stored files. There is the issue of privacy for the really paranoid, but I am not very concerned about that with the files I currently choose to mirror. I am more worried about the chance that their client develops a bug that wipes out my files, but I guess I'll take that risk.