From: Ken Brown[SMTP:k.brown@ccs.bbk.ac.uk]
Bill Stewart wrote:
and that the people who voted all existed and were unique,
That's the hard part. Do you have to give id to vote? Here we don't, so impersonation is possible. Rare I think (doing it enough times to influence a nationwide, or even a city or county -wide election would be risky) although it is rumoured to be traditional in parts of Northern Ireland - from where it was rumoured to have been exported to parts of north America :-)
One solution I've seen used in 3rd world countries is to require people who have just voted to dip a forefinger into a cup of intense, penetrating dye, which they are very unlikely to be able to remove in one day. I can state from personal experience that Silver Nitrate solution will produce stains on skin which gradually blacken in the light, and don't come off till your skin wears off. Mixing the dye with a transport agent such as DMSO would also work. Peter Trei