Normal jeans are homotopic to a cylinder with a point removed. Leg-sewn jeans are homotopic to a torus with a point removed. Both of these can be deformation retracted to a wedge of two circles (roughly: widen the puncture as far as you can).
I know the authors---it was a pleasent surprise to see them on HN this morning! The first two in particular have been working on computer-aided investigations in pure mathematics for a few years now.
I spent a long time migrating a project to use poetry. One of the reasons I opted for poetry over others was that the lockfile retained all of the environment markers in the packaging metadata, so that the lockfile could support multiple interpreters and interpreter versions, multiple platforms, etc.
I personally call ( ) "round brackets" to try and be a bit more explicit about which kind of bracket I mean, but I don't think that's a very common turn of phrase. Similarly I've picked up calling { } "brace brackets" from programming.
https://www.thinking.withportals.com/ was (is?) the big community for this. I was part of it around the time Valve released their easy map editor (the "perpetual testing initiative")---more than a decade ago now. I had the pleasure of testing the editor before its release. It was an exciting time!
Sadly that editor was geared towards single-player maps, whereas my interest was always in the coop ones. If you'll forgive the shameless plug, https://steamcommunity.com/sharedfiles/filedetails/?id=89692... was my favourite to make. I put a lot of time into that, but sadly I lost the hard drive with the map's source files some years ago. It's done quite well on the workshop---which always surprises me. I had very little idea about level design or what constitutes a fun puzzle. Beginner's luck, maybe?
It was a lot of fun/pain/curiosity to work with and fight Valve's hammer editor. I remember thinking "this feels like a tool designed to make half-life maps". I can still remember tying brushes to func_detail entities so that they wouldn't contribute visleaves. Good times!
While I'm at it: I'd recommend the "sendificator" series: https://steamcommunity.com/workshop/filedetails/?id=29165303... . These introduce a new puzzle element entirely contained within the map file. I'm guessing it must use some kind of lua script to implement it, since it's entirely contained in the map.
It's not a problem; it's an intense frustration. It is irritating to be told "here's a new message X" at your desk, only to see and hear the same notification "new message X" on a phone within a few seconds. Your phone even vibrates, as if to demand your attention and chide you for not acknowledging the message. It's an additional distraction when we're all short on time.
My previous work used a system which queued notifications for delivery. The logic was something along those lines:
- send notifications for urgent items, e.g. incoming calls, immediately to all devices
- if there are no active devices, send all notifications immediately
- otherwise send to all active devices st internally along with testers.
I ended up tweaking this; it took us a few tries to get it right. I'd be flabbergasted if Facebook messenger, iChat, discord et al haven't done something similar.