Dan Frumin
logic-adjacent ~ groningen
i post about logic, arts, and culture
Here is an ``interesting'' question I have in type theory, and it has to do with Leibniz equality.
In type theory, we can formalize a version of Leibniz equality principle on sets as a type
```
Leq(A, a, b) ≡ ∏ (P : A → hProp), P a = P b
```
where `A : hSet`. I.e. two things are equal if no proposition can distinguish them. Thus we 'explain' equality in an hSet in terms of hProp-predicates.
In case `A : hSet`, the defined Leibniz equality coincides with the usual equality. Since both types in this case are propositions, it is easy to show the logical bi-implication.
What I am interested in is if this generalizes to higher type? Suppose `A : n-Type`, and we define
```
Leq_n(A, a, b) ≡ ∏ (P : A → (n-1)-Type), P a = P b
```
what can we say in relation to the actual equality? We can still have a logical bi-implication, but I am not sure if the types are going to be isomorphic. Can anyone (dis)prove me?
pet in de hand
fiets aan de kant
wij staan stil in dit land
One of my favourite harpists is the brilliant Lavinia Meijer. And she is out with a new album, full of her own arrangements
Please check it out if you like baroque music or just harp music:
- https://open.spotify.com/album/6t5pw5WCiQlpmo0aIkejXk
- https://classical.music.apple.com/us/album/1860263402
Does anyone remember [Darcs](https://darcs.net/)? It was genuinely a nice interesting system, but seems completely dead now
Since there are a lot of type theory folks here, maybe someone can help me out
Does anyone know a good overview/reference of how to make gradual typing (somewhat) sound without destroying performance?
Salman Rushdie on Voltaire's Candide: spotting a fresh eye patch, it looks like they are going to make the whole series
https://www.youtube.com/watch?v=wgk5gXEEV9U
How to make a better pen/pencil clip by using springs
Why doesn't this exist everywhere?
Niels W Gade: Violin Concerto in D minor, Op. 56 (the "W" stands for "Winner"): https://www.youtube.com/watch?v=lecOb2MKYl8
Danish music is extremely underrated.
The dreams are coming true: France is ushering a new age of Linux. Could 2027 finally be the year of Linux on Desktop? (probably not)
https://www.zdnet.com/article/france-leaves-windows-for-linux-desktop/
An interesting survey from the Kyiv International Institute of Sociology on the attitude of Ukrainian people towards different ethnicities and nationalities.
The respondents were asked to rate different ethnicities on the scale from 1 to 10, where 1 means "I'd treat them like my family" and 7 means "I'd not allow them to enter the country"
In a true Eastern European fashion, no group has managed to get an average score below 2 (which means "I'd treat them as closed friends"). The results are in the screenshot, and the rows are as follows, from the most friendly to the least friendly: Ukrainian-speaking Ukrainians, Russian-speaking Ukrainians, Jewish citizens of Ukraine, Canadians, Germans, Poles, French, Americans, Belorussian citizens of Ukraine, Romanians, Russian citizens of Ukraine, Africans, Roma, Belorussians, and, in the very end Ukrainian and Russian citizens of Russia
Compared to a similar study in 2022, Americans fell down the list for the obvious reasons, and all the bickering with Poland is probably responsible for the Poles scoring this low
source: https://www.kiis.com.ua/?lang=ukr&cat=reports&id=1603&page=1
Maxim Vengerov plays Tchaikovsky's Violin Concerto with Tokyo Philharmonic, 1993: https://www.youtube.com/watch?v=Ydg64SXfOJI
This guy should have more subscribers on his channel!
Maxim Vengerov plays Tchaikovsky Violin Concerto (1993)
Does anyone have experience with self-hosted Git? I am currently using Gitea but it updates so fast (including security fixes) that I cannot keep up with it..
I am considering going back to just using cgit (which is annoying to configure). Does anyone have any pointers?
