user147263 is gone it seems, very recently. (I do not stalk them nor even spend much time here most days, but coincidentally something weird happened that indicated the moment of the account being gone.) There may be hundreds of closed questions that previously had a single delete vote by them, and now have none (I am speculating but have reason to think it is plausible).

That means the results of the following query may get suddenly smaller at the end of this week: data.stackexchange.com/math/query/207652/… I mention this here in case anyone else uses this list and might want to save a copy, taking advantage of the work user147263 did in finding them and starting clean up.

That's the "user with many names", right?

Yes.

[ SmokeDetector ] Offensive answer detected: How to determine if 2 points are on opposite sides of a line by dalecolin on math.stackexchange.com …

[ SmokeDetector ] Pattern-matching website in answer: If I generate a random matrix what is the probability of it to be singular? by eli ta on math.stackexchange.com …

[ SmokeDetector ] Few unique characters in answer: Three disks unique intersection contained in another circle by user2829166 on math.stackexchange.com …