vonuebelgarten

> do you have any thoughts on what causes these systems to stick to trains?

Trains are excellent for dense urban environments and better yet when integrated with another modes. I take Berlin as an example: You have fare zones and S/U-Bahn everywhere in the city center extending for to Potsdam, etc., trams in the former east, buses on the less dense parts of the city. Also trivial access to regional and long-distance trains. And it also disproves the typical excuse "You can't do that in an old city": some U-Bahn lines exists since 1902, the city got devastated by war and then there was the DDR. The reunification needed a lot of work and yet the system survived. Took me a long time to notice there was no Ubers, maybe because it was not that advantageous for people to use it and Uber Inc. just gave up instead of fighting city regulations, as they did everywhere).

I compare with the systems from my native Brazil, where public transportation ranges from pathetic inefficient on big cities to non-existent in small towns. Hell, I really miss Berlin.

This is also standard practice here in Brazil.

Why the hell aren't we migrating to the Fediverse (aka Mastodon) en masse ?

> So encryption isn't allowed, but is there any way to authenticate information sent over packet radio? Open communication has plenty of uses, but some of those can be spoiled by bad actors impersonating others.

You are not allowed to encrypt data on ham bands (this seems to happen Worldwide, it is also true here in Brazil), but there is no restriction on use of cryptographic primitives for authentication. But some countries (France, AFAIK) also require the protocol specs to be openly available, what should not be a problem in this field.

Digital signatures are Ok as long as the content of the message is not hidden (i.e. all listeners can receive and decode the information) and the transmission is identified (as usual in ham).

This is an example of title that could benefit from a simple, non-editorialized, and purely factual change: "Programming the Z3 SMT solver".

I am sure I was not the first to think it was related to Konrad Zuse's Z3.

People are too quick to understand these new terms as solely necessary to provide service. The entire paragraph is:

> "By submitting, posting or displaying Content on or through the Services, you grant us a worldwide, non-exclusive, royalty-free license (with the right to sublicense) to use, copy, reproduce, process, adapt, modify, publish, transmit, display and distribute such Content in any and all media or distribution methods (now known or later developed). This license authorizes us to make your Content available to the rest of the world and to let others do the same. You agree that this license includes the right for Twitter to provide, promote, and improve the Services and to make Content submitted to or through the Services available to other companies, organizations or individuals for the syndication, broadcast, distribution, promotion or publication of such Content on other media and services, subject to our terms and conditions for such Content use. Such additional uses by Twitter, or other companies, organizations or individuals, may be made with no compensation paid to you with respect to the Content that you submit, post, transmit or otherwise make available through the Services."

It is easy to associate the concession of license (specially the "You agree that this license includes the right for Twitter to provide, ... to other companies, organizations or individuals for the syndication, broadcast, distribution, promotion or publication ... subject to our terms and conditions for such Content use.") with the service provided ("This license authorizes us to make your Content available to the rest of the world and to let others do the same"), but I do not see where it say that Twitter can only do this for providing the service. AFAIK, Twitter still can, for example, sell photos to a news agency through this same terms.

Of course, IANAL.

Their strategy is particularly awesome: a hundred of small short-lived satellites (really small, they're 3-unit cubesats, 30x10x10 cm) operating in a swarm. No big deal if a single one is lost: operation can continue with other ones once they are in position. Also, costs are spread due the possibility of servicing several customers simultaneously in separate locations around the globe.