[EM] Paper by Ron Rivest

[fsimmons at pcc.edu]

The Rivest lottery is non-monotone, but here is a monotone, clone independent lottery that always selects from the uncovered set:
1.  Let C1 be a candidate chosen by random ballot.  If C1 is uncovered, then C1 wins.
2. Else use random ballot to find a candidte C2 that covers C1.  If C2 is uncovered, then C2 wins.
3. Else use random ballot to find a candidte C3 that covers C2.  If C3 is uncovered, then C3 wins.
4. Else use random ballot to find a candidte C4 that covers C3.  If C4 is uncovered, then C4 wins.
etc.
Note that the clone independence has the nice character of the "Condorcet Lottery" and the Rivest method:  the conditional probability that a member C of the clone set S is chosen given that the winner is in the clone set is equal to the probability that C would be chosen from S if the method were applied soley to S.
FWS
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