Alice and Bob play the following game with two six-sided dice (numbered $1$ to $6$):
Each player devises a (possibly non-deterministic) strategy. An example strategy for each player could be:
In fact, these two strategies together form a Nash equilibrium. That is, given that Bob is using his strategy, Alice's strategy minimises the expected payment; and given that Alice is using her strategy, Bob's strategy maximises the expected payment.
With these strategies the expected payment from Alice to Bob is $\frac{145}{36}\approx 4.027778$.
To make the game more interesting, they introduce a third (six-sided) dice:
Supposing they settle on a pair of strategies that form a Nash equilibrium, find the expected payment from Alice to Bob, and give your answer rounded to six digits after the decimal point.