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From a technical standpoint, a few lines of code is all that is needed. From a socioeconomic standpoint it is next to impossible.

Yes I think so. I'm talking about it and trying to come up with a solution to it.

No, because anybody can set up another account and cross-vote essentially for themselves. In my most recent article I treat voting-for-same-user as one algorithm, whether for self or a sock-puppet of self.