This question from March 2020 points out that many questions/answers link to papers at the http://front.math.ucdavis.edu/ frontend instead of at the arXiv itself, but that the frontend had been down a few weeks. There are c.600 affected questions and it looks like a large proportion of the links...

``Proofs without words'' is a popular column in the Mathematics magazine. Question: What would be a nice way to characterize which assertions have such visual proofs? What definitions would one need? I suspect that in order to make this question precise, one will have to define a computational...