@psephomancy said in GPT and I invented a new voting system metric?:

@toby-pereira said in GPT and I invented a new voting system metric?:

I think if a measure isn't cloneproof it's probably not a good measure.

Why would that matter for a measure?

Because you can have a candidate that is the closest to being the Condorcet winner but not the Copeland winner. E.g.

14: A>B>C

4: B>C>A

12: C>A>B

A>B - 26:4

B>C - 18:12

C>A - 16:14

A has the biggest winning margin and smallest defeat, and is the nearest to a Condorcet winner by any reasonable measure. But then you can clone C and have a C1 and C2 but where C1 is always ranked above C2.

In this case A now has two defeats (against C1 and C2) so loses to both B and C1 in Copeland. But A is still the nearest to a Condorcet winner in terms of defeat sizes, so I would say they are still the "most Condorcet" winner.