[EM] Schulze STV question
km_elmet at t-online.de
Sun Jan 15 11:00:46 PST 2017
On 01/15/2017 07:19 PM, Andrew Myers wrote:
> CIVS has an (implemented) proportional mode that operates over sets of
> candidates (http://civs.cs.cornell.edu/proportional.html) and it does
> get used. However, in principle it can be much less efficient than
> regular Condorcet for the reasons Markus identified.
An interesting challenge: Find a method that works like Schulze STV or
proportional CIVS (that is, compares assemblies) but there is some
convexity or other structure to the assembly scores so that a local
search (or a polytime search of some other form) is guaranteed to find
the optimal assembly, while the system as a whole still obeys desired
properties like Droop proportionality, monotonicity, teaming
I suspect that (very handwavy) to achieve a certain type of
proportionality, you have to solve a set covering problem. Certainly,
set covering appears in a lot of PR problems (e.g. Monroe). But it might
be doable to settle for less than perfect proportionality while still
being Condorcet and obeying the DPC.
STV-ME (the STV version of BTR-IRV) is Condorcet in the single-winner
case and I think it passes the DPC, but it can't be easily formulated as
an assembly-vs-assembly method. It's not monotone either.
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