[bombcar]

You could in theory make it decentralized-ish depending on the requirements. For example they could allocate blocks of seats to vendors and if you bought one of those seats you could buy it “offline” to be synced later.

But it’s probably not worth the hassle and once the ticket is sold you can have it be signed by the centralized system so you can verify the signature offline easily.

[iudqnolq]

I don't think that theory works out in practice because they have not that many seats in the trains, a lot of vendors, vendors that book very small and irregular numbers of tickets on routes, and sometimes very few or no extra seats. So you'd need to reallocate the blocks by demand quite frequently, at which point it's morally a shitty centralized system.

And with every clever decentralized solution there's another feature request that adds more complexity. I just remembered some trains have displays above seats that tell you if it's reserved.