Psephology • Social choice theory • Spoiler effect • Comparison of electoral systems • Arrow's impossibility theorem • Strategic voting • Gibbard's theorem • McKelvey-Schofield chaos theorem • Redistricting • Proportional representation • Fraud detection

A Haskell language library dedicated to the study of psephology.

• Compiled using the Glasgow Haskell Compiler, version 9.12.2
• Cabal version 3.12.1.0 (later Cabal versions are finicky with HLS)
• Docker version 28.4.0

Feature list

• Algorithms to determine the victor under various single-winner election systems, including:
  • Borda count
  • Condorcet voting
  • First-past-the-post
  • Instant-Runoff Voting
  • Rated voting (range, STAR, graduated majority)
  • Sortition
  • Two-round system
  • and tools to evaluate the susceptibility of these systems to pathologies.
• Seat projections
  • Multilevel regression with poststratification (MRP) polling
  • Swingometer
• Algorithms to determine seat allocation under various party-list proportional representation systems, including both the highest averages method and the largest remainder method.
  • Tools to evaluate the proportionality of these systems.
  • Tools to evaluate the susceptibility of these systems to pathologies.
• A new algorithm to reapportion voting districts.
• Tools to evaluate and study the spoiler effect.
• Tools to devise and study voting strategies (strategic voting).
• Interface to handle .blt files.
• Tools to evaluate voting system efficiency.
• Tools to identify voter fraud through a statistical analysis of published election results.
• Tools to study the McKelvey-Schofield chaos theorem.
• Tools to generate synthetic voters under the single-peaked preferences model.
• and many others!

Docker

Use Docker to run test suite.

$ docker build -t psephology .
$ docker run --rm -t psephology # run tests

Using a custom GHC version:

$ docker build -t psephology --build-arg GHC_VERSION=${GHC_VERSION} .

Or you can run one of the examples:

$ docker run --rm -t psephology cabal run example-${EX}

Docs

Building the Docker container using the command above will produce a directory called docs/. You can then pop into docs/index.html.

TODO list

Planned features (not necessarily planned for first release):

• Proxy cycles
• Convert a list of formal voters into a list of theoretical voters (use k-means)
• System-wise efficiency
• Finish weak orderings
• Polsby-Popper
• Test suite
  • Property lists

Requests and suggestions are welcome!