Jon Pretty

You might be onto something... but I can't be sure. ;)

Presuponing the torturer allows the prisoner to rearrange the cards on the envelopes or leaving them stacked in an order that won't be reshuffled before the next prisoner then it is trivial.

No, that's not permitted. Every prisoner is presented with exactly the same envelopes in exactly the same state.

Sorry I missed the clarifications, but the "each prisoner...for each" confused me. It must surely mean all prisoners can see the opening of envelopes for the rest of the prisoners, thus being able to map the whole envelope contents with the over 30% survival probability.

Nope. It's not based on someone seeing someone else's openings. @propensive thanks for sharing this, was cool thinking about it.

Then I'm really looking forward to know how that 30% survival probability is even possible if there is no information sharing of any kind.

Communication is not permitted, but sharing of new information is possible. The choices of which envelopes to open can be made serially.

This might confuse the people. Every prisoner does all his picks 1 by 1 in a row, but can decide on every pick what to pick next.