coastal984 writes: Facebook has rolled out a sweeping change to profiles few have noticed, without users' permission: Your email listing has been changed from whatever you had posted to an @facebook.com address. You have to go and change it back manually to undo the change. One would have thought Facebook would have learned it's lesson by now, but apparently they have not.
We warn the reader in advance that the proof presented here depends on a
clever but highly unmotivated trick.
-- Howard Anton, "Elementary Linear Algebra"