Suddenly I'm seeing a lot of unrendered $\TeX$ code. Is it just me, or did mathJax suddenly stop working here?
(The reason the software would not allow me to post the question above was "It does not meet our quality standards. A wild guess: it was too short. I'm padding it here in order to find out. Whoever wrote that sarcastic statement purporting to explain the reason should have used his head instead.)