You can do A' in some US states... you can vote by mail/early vote, and then later request they spoil that ballot and do it again, or by voting on election day the mail-in is invalidated.

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grg0 3 hours ago | parent [-]

The US voting system is probably not a good starting point for modeling such systems :)

	▲	cryptonector 2 hours ago \| parent \| next [-]
		There is no "US voting system". Each of the 50 States have their own systems, often several systems, and where there are several systems it's the counties that pick a system that suits them.
	▲	sam1714 2 hours ago \| parent \| prev [-]
		I'm confused. Can you explain the exact issues created by this repudiation system practiced by US states? Maybe there's a real issue that hasn't been addressed that I am unaware of. Or is this a knee-jerk America Bad?