It doesn't matter. When people say efficient market, they mean that the market knows whatever is knowable by the present time using current technologies. They don't mean that the market knows everything that's theoretically knowable using unknown/impossible algorithms.
Before there were computers in an efficient market (supposing one exists), the current prices would reflect everything that is known and can be computed/deduced without computers by the present time.
Anyway, the paper misunderstands "known" to mean "anything which can theoretically be known", which obviously includes solutions NP-hard problems. It's just that nobody claims that's what efficient markets are.
Before there were computers in an efficient market (supposing one exists), the current prices would reflect everything that is known and can be computed/deduced without computers by the present time.
Anyway, the paper misunderstands "known" to mean "anything which can theoretically be known", which obviously includes solutions NP-hard problems. It's just that nobody claims that's what efficient markets are.