Blackjack basic strategy makes the assumption that the player is playing independently, with one person's decision to hit/stand having no affect on another player's decision to hit/stand. If the results of every single hand were independent from each other, then there would be no way to improve upon basic strategy and gain a positive expected return.
Blackjack hands, however, are not independent events. Card counting takes advantage of the fact that the next hand is not independent of previous hands, due to the limited number of decks in the shoe.
A few days ago, I realized that there might be another way to gain an advantage by using the fact that the results for individual players during a single round are not independent of each other.
For example, most players will win when the dealer has a weak hand, and most players will lose when the dealer has a strong hand. Also, one player's cards reveal information about the probable outcome for both other player's hands and the dealer's hands for that particular round (even when there is a continuous shuffle machine being used).
If player A and player B have expected returns that are not independent of each other, is there a way for them to work together to alter their strategy in a way as to decrease the house edge?