OpenTally/README.md

# OpenTally

OpenTally is an application for counting various preferential voting elections, with an academic focus, and emphasis on configurability.

OpenTally may be used in a number of different ways:

* as an online web application, no installation or special software required
* as a standalone command line application
* as a Rust library within another application

## Features

OpenTally accepts data in the [BLT file format](https://yingtongli.me/git/OpenTally/about/docs/blt.md), and can count votes using:

* weighted inclusive Gregory STV (e.g. [Scottish STV](https://www.legislation.gov.uk/ssi/2011/399/schedule/1/made))
* unweighted inclusive Gregory STV (e.g. [Australian Senate STV](https://www.legislation.gov.au/Details/C2020C00400/Html/Text#_Toc59107700))
* exclusive Gregory STV (e.g. [PRSA 1977](https://www.prsa.org.au/rule1977.htm) and [ERS97](https://www.electoral-reform.org.uk/latest-news-and-research/publications/how-to-conduct-an-election-by-the-single-transferable-vote-3rd-edition/))
* [Meek STV](http://www.dia.govt.nz/diawebsite.NSF/Files/meekm/%24file/meekm.pdf) – with [tree-packed ballots](http://www.votingmatters.org.uk/ISSUE21/I21P1.pdf) for efficient computation
* [Wright STV](https://www.aph.gov.au/Parliamentary_Business/Committees/House_of_Representatives_Committees?url=em/elect07/subs/sub051.1.pdf)

OpenTally is highly customisable, including options for:

* different quotas and quota rules (e.g. exact Droop, Hare)
* calculations using fixed-point arithmetic, guarded fixed-point ([quasi-exact](http://www.votingmatters.org.uk/ISSUE24/I24P2.pdf)) or exact rational numbers
* different tie breaking rules (backwards, random, manual) with auditable deterministic random number generation
* multiple constraints (e.g. affirmative action rules)
* equal rankings

## Online usage

After preparing the [BLT file](https://yingtongli.me/git/OpenTally/about/docs/blt.md), open the web UI. Select the BLT file, and click *Count*. OpenTally will count the election and display the results in a count sheet.

By clicking *Show advanced options*, you can customise the options used for the count. A detailed explanation of the various options can be found [here](https://yingtongli.me/git/OpenTally/about/docs/options.md).

Once the count is complete, you can click *Print result* to generate a printable result report.

## Command line usage

OpenTally may also be invoked as a command line application. Run `./opentally --help` to view help.

For example, run `./opentally stv path/to/blt_file.blt --ties backwards random --random-seed foobar`.