[mikorym]

Not sure what you are saying. Mathematicians were not even allowed to travel abroad [1] and any "concessions" were essentially as it pleased the USSR state. Only from 1990 was movement free in the true sense of the word.

[1] An example was when Margulis won the Fields medal: https://en.wikipedia.org/wiki/Grigory_Margulis. There are many other examples too.

[gdy]

What does that have to do with sharing knowledge in the USSR and the countries in the Soviet block?

It was never in Soviet ideology to hide knowledge behind paywalls. See, for example, this [0] post about Mir publishing house and warm comments of Indians who grew up with their books. Sci-hub's ideology is just continuation of this approach.

[0] https://news.ycombinator.com/item?id=21352277

[mikorym]

> Sci-hub's ideology is just continuation of this approach.

Actually, that was the point of what I was saying—the mathematicians had to be inventive and thus passed around preprints that they knew would also be read in the West.

[gdy]

Why did they have to be inventive? Please provide a source.

[mikorym]

[2] Also the 1970 Fields medal: https://en.wikipedia.org/wiki/Sergei_Novikov_(mathematician)