This seems like a trivial problem, but dumb me thinked forever without proving any solution as the optimal.
So the problem is, given $n$ people, each with wealth $w_1,\dots ,w_n$, with $w_i$ being any real number, how to move money among the $n$ people so that everybody ends up being equally wealthy, and minimizes the the total transaction volume?
One trivial solution is to have everybody first pile up all the money on one person, then that one person divides the money equally and distributes it. (Side note: sounds very like a communist state...). However this can result in highly unoptimal transaction volumes: indeed it is almost never optimal and usually very unoptimal since everybody except the distributor needs to move all their money.
Is there a standard algorithm to solve this problem?