Søren Fuglede Jørgensen @fuglede@mastodon.social

New blog post: Burau and the infinite parking garage.

On a fun open problem in mathematics, easy to explain and implement an algorithm for, deceptively hard to find the solution to.

https://fuglede.dk/en/blog/burau-and-the-infinite-parking-garage/

Fraction of B.1.1.7 in Denmark is /down/ since last week. This is spooky. B.1.525 enough to account for some 4-5% of week 11 cases.

Initial week 11 data for B.1.1.7 situation in Denmark.

Initial week 10 data for B.1.1.7 situation in Denmark available. Counts doubling roughly every 3 weeks. Reopening in process.

Fresh B.1.1.7 counts. BOTE doubling rate ~2-3 weeks. Signs B.1.1.7 causes 60% more admissions/case, which gets us back to December levels fairly soon. Reopening in process.

More week 9 data for Danish B.1.1.7 counts. Puts us straight into the worst end of the previously reported confidence interval for week 9.

Initial information from week 9. This one could be worse for once!

More data for week 8 is in. Week 8 estimate slightly up.

Updated estimated number of COVID cases caused by B.1.1.7 variant in Denmark. Note: Week 8 data incomplete, actual count will likely rise further.

Estimated number of COVID cases caused by B.1.1.7 variant in Denmark keeps climbing. Meanwhile Danish govt initiates reopening.

Certainly not Texas levels of crazy but electricity spot prices did see some spikes of high highs around here during the cold.

Best part about https://www.state.gov/biographies/donald-j-trump/ is how the time (but not the date) seems to be changing all the time.

Numerical instability in the simulation?

More seriously, what do these folks mean when they say "70% more contagious"? Are we talking about how it affects what the exponential rate would behave like in the wild? That e.g. what would otherwise be a situation with a 0.9 growth rate should now be a 1.53 growth rate instead?

Tænker du på det samme som mig B1? Det tror jeg faktisk, B117! Det er pandemitid!

SciPy 1.6.0 just made it in before the end of 2020! [0] I'm personally quite happy with how its new matching solver came out. [1]

[0] https://mail.python.org/pipermail/scipy-dev/2020-December/024468.html
[1] https://docs.scipy.org/doc/scipy/reference/generated/scipy.sparse.csgraph.min_weight_full_bipartite_matching.html

Yet another December well spent with #AdventOfCode! Yet, feels so good to get rid of the 5:30 alarm.

https://adventofcode.com/
https://github.com/fuglede/adventofcode

I was a bit surprised to see that comma.ai explicitly values programming competition participants in recruiting, but seeing geohot feature on https://adventofcode.com/2020/leaderboard explains a lot.

Back of the envelope: So, according to a more or less randomly picked internet source [0], 1 mink causes about 10 kg of CO2eq emissions over its lifetime. So, culling 15 million of them will save us about 150000 tons CO2eq per year (not counting production of whatever people will wear instead). Compare that with the Danish target of reducing emissions by 20 million tons CO2 per year by 2030. Did we just get about 1% closer to that target?

[0]: https://www.cedelft.eu/publicatie/the_environmental_impact_of_mink_fur_production/1131

Danish investment bank Saxo Bank recently introduced minimum brokerage fees on a 1 month notice; as such, customers with small positions are now forced to either close immediately (paying a fee to Saxo Bank) or wait (paying an even larger fee to Saxo Bank); pest eller kolera, as we'd say.

If this is legal(?), what would keep a unscrupulous investor platform from introducing sky-high fees to force the hands of smaller customers?

PSA: Check out Mars right now (east-southeast from my corner of the world). It's that yellowy-orangey thing that's way brighter than it normally is: It's closer to us now than it's going to be for some 15 years.