Beachhenge linkage

On the scale of stupid things the US government is doing this is pretty small, but they appear to be banning the census bureau from any effective methods of privacy-preserving information release, and in particular from adding noise to their data to help create differential privacy ($\mathbb{M}$, via). Sadly, taking away valuable disclosure avoidance tools doesn’t make fundamental trade-offs go away.
Bipartite matching is in $\mathsf{NC}$ ($\mathbb{M}$). New preprint by Abhranil Chatterjee, Sumanta Ghosh, Rohit Gurjar, Roshan Raj, and Thomas Thierauf, solving a longstanding open problem. This is apparently enough to solve the related open problem of constructing depth-first search trees in parallel, but the non-bipartite version of matching is still open.
Illustration of ranked choice voting and how it worked in Maine’s gubernatorial Democratic primary ($\mathbb{M}$).
My father had a cat named Hillary, after Sir Edmund ($\mathbb{M}$). One of mine also likes high places. The two perches in these photos can be reached from partway up, but he can jump from the floor to almost the same height, well above my head.
Interactive demo of the Finsler–Hadwiger theorem ($\mathbb{M}$), that when two squares share a vertex, a third square is formed by their centers and the midpoints of segments connecting the vertices adjacent to the shared vertex.
Peter Rowlett reviews David Singmaster’s Mathematical Gazeteer of the British Isles ($\mathbb{M}$), “a treasure trove of information about local connections to the history of mathematics in the British Isles”.
Bridges 2026 Exhibition of Mathematical Art, Craft, and Design ($\mathbb{M}$).
“Möbius” sculpture, Masami Kodama, 2010.
Springer Nature retracts two old papers by Max Planck, one because it was also published elsewhere, another because someone else published something else with the same title ($\mathbb{M}$), and then tries to sell you the blank pdf of the retracted paper for $40. They claim that the retraction can only be discussed with Planck himself (long dead, of course). Who knows how many other publications by more-obscure authors they are also removing for equally spurious reasons?
Found at Little River Beach in Mendocino County, California ($\mathbb{M}$):
Why does paper fold so well ($\mathbb{M}$)? BBC CrowdScience, 26 minute audio link. I didn’t have much luck playing it in FireFox with an adblocker, and instead had to run Safari and sit through the same two ads twice (because it still didn’t work the first time through), but maybe the direct media file download (via) will work better.
In two-dimensional general relativity, particles form cone points with angular deficit proportional to their mass, so by Descartes’ theorem on total angular defect the total mass of a spherical space is fixed, and by Alexandrov’s theorem on polyhedra any such space has the metric structure of the surface of a convex polyhedron.