[EM] multiwinner election space plots

[Brian Olson]

http://bolson.org/voting/sim_one_seat/20090810/

I think a few of these plots show Single Transferrable Vote behaving  
badly in the same ways IRV does, with discontinuities and irregular  
solution spaces.

I also ran Condorcet and IRNR using combinatoric expansion.  
Combinatoric variants of single winner election methods adapt to  
multiwinner situations by enumerating all possible winning sets of the  
available choices and using a simulated voter's preferences on the  
choices in each set to determine a preference for each winner-set.  
Voting on the n-choose-k preferences for winner-sets then procedes as  
for a single-winner election.

I think based on this I'm going to have to think more about making  
native multiwinner methods. Combinatoric expansion gets pretty  
expensive for large numbers of choices or seats to elect. I had been  
kinda resigned to STV being the state of the art in multiwinner  
methods, but we seriously ought to be able to do better.