Tootfinder

On the role of connectivity in Linear Logic proofs
Raffaele Di Donna, Lorenzo Tortora de Falco
https://arxiv.org/abs/2506.21678 https://

On the role of connectivity in Linear Logic proofs
We investigate a property that extends the Danos-Regnier correctness criterion for linear logic proof-structures. The property applies to the correctness graphs of a proof-structure: it states that any such graph is acyclic and that the number of its connected components is exactly one more than the number of nodes bottom or weakening. This is known to be necessary but not sufficient in multiplicative exponential linear logic (MELL) to recover a sequent calculus proof from a proof-structure. We…

A while ago the media reported that most of the long-distance "suburban" trains between #Wrocław and #Poznań will be discontinued, and instead one will have to change trains midway. Irrespective of whether it's actually going to happen, let's consider it.
As you can probably tell by now, I'm not a stranger to changing trains. In fact, there are some direct connections that I do criticize. For example:
• Poznań — Szczecin — Świnoujście, where arriving at Szczecin Główny and turning back to leave the city is a waste of time. It's better to change trains at Szczecin Dąbie.
• Poznań — Krzyż — Kostrzyn, where instead of using a single railbus, you can use a larger EMU for the Poznań — Krzyż segment, and a smaller DMU for Krzyż — Kostrzyn (in fact, only recently the "direct" Poznań — Kostrzyn train involved just that, but it was supposed to be temporary).
However, good matches are the key. Say:
1. Max 10 minutes (when there are no delays) from one train to the other.
2. "Door-to-door" transfer — without having to carry all your luggage across platforms.
3. Reliable connection — if one train is delayed, the other train waits for it (or there are so many alternatives that it doesn't have to).
Can such a thing happen on Poznań — Wrocław route? I have my doubts.
I've been using these trains for years, and I can say this: there is no effort to match train from/to Poznań with other trains in Wrocław. Sometimes the trains depart 10 minutes before the first train from Poznań arrives, sometimes I need to transfer in 10 minutes, and sometimes I have to wait over an hour. And the same in the other direction.
Perhaps things would actually improve if the route is split. Perhaps people would actually care. Maybe even the trains would be fitted better to the timetable in Wrocław. But I find it hard to believe.
EDIT: One final thought — since there is no real reason to split these connections (except for profiteering), why make travellers' lives harder?
#rail

On the Consistency of Peano Arithmetic in a Proof-theoretic Semantics for Classical Logic
Alexander V. Gheorghiu
https://arxiv.org/abs/2506.22326 https://

On the Consistency of Peano Arithmetic in a Proof-theoretic Semantics for Classical Logic
We give a proof of the consistency of Peano Arithmetic (PA) within a novel semantic framework for classical logic due to Sandqvist. The argument proceeds by constructing an object $\mathfrak{A}$ -- the arithmetic base -- which supports all axioms of PA and can be shown to not support $\bot$, relative to a well-foundedness assumption equivalent to $ε_0$-induction. This framework belongs to the paradigm of proof-theoretic semantics, that unlike model-theoretic approaches, offers a finitistically…

Bra och intressant rep av Henrik Brandão Jönsson och Adriano Mérola Marotta från Ciudad Jušrez. https://www.dn.se/varlden/kartelledaren-el-chapos-advokat-kan-bli-vald-till-domare-i-mexiko/

Kartelledaren El Chapos advokat kan bli domare i Mexiko
Kartelledaren El Chapos tidigare advokat kan väljas när Mexiko håller allmänt domarval.

Duitse onrust over nationale goudstaven in VS. ‘Het is ons geld, het moet worden teruggebracht’ - NRC
https://www.nrc.nl/nieuws/2025/…

I've been using #kicad to reverse my dad's frequency standard, locked off BBC Radio4 198kHz. I'm sure there are bits I've not got right, but the vague shape is there - a loop with input amp/filters from the receiver, which ends up combining with the divided output (at 2kHz) with the output of a 10MHz crystal oscillator based on a 74HC00; that combined result ends up driving a var…

Dissipative Kondo physics in the Anderson Impurity Model with two-body losses
Matthieu Vanhoecke, Naoto Tsuji, Marco Schir\`o
https://arxiv.org/abs/2506.22302

Dissipative Kondo physics in the Anderson Impurity Model with two-body losses
We study a dissipative version of the Anderson Impurity model, where an interacting impurity is coupled to a fermionic reservoir and exposed to Markovian dissipation in the form of two-body losses. Using a self-consistent hybridization expansion based on the Non-Crossing Approximation (NCA) we compute the dynamics of the impurity, its steady-state and spectral function. We show that the interplay between strong Coulomb repulsion and correlated dissipation gives rise to robust signatures of Kond…

#Wordle 1,442 4/6*
⬜⬜⬜⬜⬜ <1% of 214,516 (878)
⬜⬜🟨⬜⬜ 0 of 49 (45)
🟨⬜⬜🟩🟩 0 of 0 (1)
🟩🟩🟩🟩🟩
WordleBot
Skill 91/99
Luck 39/99
I liked today's wordle. Because of how the clues led me to the word. I enjoy the logic of it, at least when I'm not struggling forever to find a word that fits.

So #Gentoo #Python eclasses are pretty modern, in the sense that they tend to follow the best practices and standards, and eventually deal with deprecations. Nevertheless, they have a long history and carry quite some historical burden, particularly regarding to naming.
The key point is that the eclasses were conceived as a replacement for the old eclasses: "distutils" and "python". Hence, much like we revision ebuilds, I've named the matching eclasses "distutils-r1" and "python-r1". For consistency, I've also used the "-r1" suffix for the remaining eclasses introduced at the time: "python-any-r1", "python-single-r1" and "python-utils-r1" — even though there were never "r0"s.
It didn't take long to realize my first mistake. I've made the multi-impl eclass effectively the "main" eclass, probably largely inspired by the previous Gentoo recommendations. However, in the end I've found out that for the most use cases (i.e. where "distutils-r1" is not involved), there is no real need for multi-impl, and it makes things much harder. So if I were naming them today, I would have named it "python-multi", to indicate the specific use case — and either avoid designating a default at all, or made "python-single" the default.
What aged even worse is the "distutils-r1" eclass. Admittedly, back when it was conceived, distutils was still largely a thing — and there were people (like me) who avoided unnecessary dependency on setuptools. Of course, nowadays it has been entirely devoured by setuptools, and with #PEP517 even "setuptools" wouldn't be a good name anymore. Nowadays, people are getting confused why they are supposed to use "distutils-r1" for, say, Hatchling.
Admittedly, this is something I could have done differently — PEP517 support was a major migration, and involved an explicit switch. Instead of adding DISTUTILS_USE_PEP517 (what a self-contradictory name) variable, I could have forked the eclass. Why didn't I do that? Because there used to be a lot of code shared between the two paths. Of course, over time they diverged more, and eventually I've dropped the legacy support — but the opportunity to rename was lost.
In fact, as a semi-related fact, I've recognized another design problem with the eclass earlier — I should have gone for two eclasses rather than one: a "python-phase" eclass with generic sub-phase support, and a "distutils" (or later "python-pep517") implementing default sub-phases for the common backends. And again, this is precisely how I could have solved the code reuse problem when I introduced PEP517 support.
But then, I didn't anticipate how the eclasses would end up looking like in the end — and I can't really predict what new challenges the Python ecosystem is going to bring us. And I think it's too late to rename or split stuff — too much busywork on everyone.

"""
The barbarian role of cultural demolition crew is especially important when you consider how often cultural reconstruction is needed. Many of Rome’s glaring defects — exploitation, authoritarianism, corrupt self-aggrandizement — flow from deeply human tendencies. Time and again they’ve transformed promising civilizations into decaying, oppressive monstrosities. Time and again, history seems to cry out: Bring on the demolition crew! And time and again barbarians cheerfully respond to the call. Their previous massive wreaking of destruction, near the end of the second millennium B.C., had come after civilization went through centuries of apparent ossification.
In a way, barbarians are just a special case of that general and potent zero-sum dynamic in cultural evolution: brutal competition among neighboring societies. This rivalry renders ossified cultures vulnerable to a makeover, minor or major. They may be taken over by a vast neighboring civilization, which will revamp them in its image. Or they may be infiltrated and perhaps even disassembled by barbarians, paving the way for future reassembly. Or they may revive and prevail — an example of the “challenge and response” dynamic stressed by Arnold Toynbee. In any event, the point remains the same: however deeply human the tendencies of exploitation, authoritarianism, and self-aggrandizement, cultures that surrender to them may not be long for this world.
"""
(Robert Wright, Nonzero: The Logic of Human Destiny)
Is it time for the barbarians now? Or perhaps we — here on Fedi — are the barbarians.