We've been using Zoobuh for several years and are very satisfied. It has an easy interface for the kids and you can set up a whitelist for incoming and outgoing email.
The extension into higher dimensions is that a simply-connected, closed n-manifold with the same homotopy groups as the n-sphere is homeomorphic to the n-sphere. For a 3-manifold, you don't have to say the bit about homotopy groups . . . that follows from the simply-connected assumption and Poincare duality.
Slashdot Mirror
We've been using Zoobuh for several years and are very satisfied. It has an easy interface for the kids and you can set up a whitelist for incoming and outgoing email.
Repost: February story
Now, I don't know if you're being serious or if you're just ignorant about Windows PCs.
Yes, they're not 100% secure. But, there are ways to limit access based on the type of userid.
I guess what I meant was, one can elevate any user account to Administrator pretty quick on an NT box.
If you have physical access to a Windows box, pretty much anything goes, software included.
The extension into higher dimensions is that a simply-connected, closed n-manifold with the same homotopy groups as the n-sphere is homeomorphic to the n-sphere. For a 3-manifold, you don't have to say the bit about homotopy groups . . . that follows from the simply-connected assumption and Poincare duality.