[EM] Depicting PR-STV in an issue space

[Kevin Venzke]

Hello,

Here's a new feature that tries to show graphically the outcomes of random STV
elections. There are always 10 candidates, but you can control the number of voters,
the plot height (vs. the width), how far down voters' sincere rankings they rank,
and how many seats will be filled. (So, you can reduce the seats to one to see IRV
if you wanted.) There are a few voter distribution options.

The ranking threshold and number of seats to fill are dynamic controls, so you can
change them without rerolling everything.

votingmethods.net/stvplot

One interesting phenomenon is how truncation can change the apparent Condorcet
winner or Smith set. There are some notations for this.

My original interest was the three-seat case with a plot close to 1D, and the
likelihood that this would carve out a clear center. This could feed a second round
of voting with three finalists. Some notations specific to three seats remain, but I
guessed there could be more interest in STV in general.

Kevin
votingmethods.net