History#

0.12.0 (2025-02-19): Accelerations and Bug Fixes#

  • In Rule and its subclasses, add option precheck_heuristic (heuristic precheck before computing CM). In earlier versions of SVVAMP, this precheck was automatically activated for all rules. However, this heuristic is costly. Hence, for rules where computing CM exactly is cheap, it is now deactivated by default.

  • Accelerate GeneratorProfileIc and GeneratorProfilePerturbedCulture.

  • Rename “IRV-immune candidate” to “super Condorcet winner”.

  • Fix bug in Profile.exists_super_condorcet_winner.

0.11.0 (2024-10-18): Conversion to Poetry#

  • Conversion to Poetry instead of Setuptools.

  • The official compatibility of SVVAMP is now with Python 3.10, 3.11, and 3.12.

0.10.0 (2023-09-29): New profile generators, voting rules and CM algorithms#

  • Add GeneratorProfileIc: Profile generator using the ‘Impartial Culture’ model.

  • Add GeneratorProfilePerturbedCulture: Profile generator using the ‘Perturbed Culture’ model.

  • Add GeneratorProfileUnanimous: Profile generator with identical voters.

  • Add RuleKApproval: k-Approval.

  • Add RuleSlater: Slater method.

  • Improve CM algorithms for RuleBaldwin, RuleCopeland, RuleIRVDuels, RuleKemeny, RuleKimRoush, RuleNanson, RuleRankedPairs, and RuleSplitCycle.

0.9.1 (2022-03-24): Compatibility issues#

  • GeneratorProfileIanc is now compatible with Python < 3.8.

  • However, starting from this release, the official compatibility of SVVAMP is with Python 3.8, 3.9 and 3.10 (no support for Python 3.6 and 3.7).

0.9.0 (2022-03-24): GeneratorProfileIanc#

  • Add GeneratorProfileIanc: profile generator for the Impartial, Anonymous and Neutral Culture.

0.8.3 (2021-08-01): Fix bug in ExperimentAnalyzer#

  • Fix bug in ExperimentAnalyzer: for StudyRuleCriteria.numerical_criteria, the aggregation was not done properly.

  • Several cosmetic changes in ExperimentsCompiler.

0.8.2 (2021-07-29): Necessary coalition size to break IRV-Immunity#

  • Add Profile.necessary_coalition_size_to_break_irv_immunity: necessary coalition size to break IRV immunity (for each candidate different from the IRV-immune candidate, if one exists).

  • Use this notion to improve the bound necessary_coalition_size_cm_ for RuleCondorcetAbsIRV, RuleCondorcetVtbIRV, RuleExhaustiveBallot, RuleICRV, RuleIRV, RuleIRVAverage, RuleSmithIRV, RuleTideman and RuleWoodall.

0.8.1 (2021-07-29): Use IRV-immune candidate for UM#

  • RuleCondorcetAbsIRV, RuleCondorcetVtbIRV, RuleExhaustiveBallot, RuleICRV, RuleIRV, RuleIRVAverage, RuleSmithIRV, RuleTideman and RuleWoodall: add a precheck for UM based on the notion of IRV-immune candidate.

0.8.0 (2021-07-29): IRV-immune candidate#

  • Introduce the notion of IRV-immune candidate. A candidate w is IRV-immune iff in any subset of candidates containing w, the plurality score of w is more than n_v / card(subset). This implies that in IRV (and most related rules), w is the winner and CM is impossible.

  • Add Profile.exists_irv_immune_candidate: whether there exists an IRV-immune candidate.

  • Add Profile.c_might_be_there_when_cw_is_eliminated_irv_style: whether a candidate c might be present in a round where the Condorcet winner is eliminated, IRV-style. In IRV (and most related rules), this condition is necessary to be able to cast CM in favor of c.

  • Use the above mentioned notions to improve the CM algorithm of RuleCondorcetAbsIRV, RuleCondorcetVtbIRV, RuleExhaustiveBallot, RuleICRV, RuleIRV, RuleIRVAverage, RuleSmithIRV, RuleTideman and RuleWoodall.

  • Add a UM precheck before CM in RuleSmithIRV, RuleTideman and RuleWoodall.

0.7.0 (2021-07-28): Better bounds for CM#

  • Introduce a heuristic method to improve the bounds necessary_coalition_size_cm_ and sufficient_coalition_size_cm_ in the case of rules based on rankings.

  • Bug fix: in previous version (0.6.12), the IRV-CM precheck for UM was not activated for RuleCondorcetVtbIRV.

0.6.12 (2021-07-28): Fix bug in PluralityEliminationEngine#

  • Fix bug in PluralityEliminationEngine: the previous version used to modify the original profile, which was not desired.

  • PluralityEliminationEngineProfileUM relies only on preferences_borda_rk and not on preferences_rk. This accelerates RuleSmithIRV.

  • RuleCondorcetAbsIRV and RuleCondorcetVtbIRV: before computing UM, we test whether IRV is CM. If not, then we can conclude that Condorcet-IRV is not CM, and in particular not UM.

  • Minor acceleration for RuleWoodall when the IRV winner is in the Smith set.

0.6.11 (2021-07-28): Accelerate ProfileUM#

  • ProfileUM: implement a dedicated implementation for plurality_scores_rk and plurality_scores_ut.

0.6.10 (2021-07-28): PluralityEliminationEngine#

  • Add PluralityEliminationEngine and its subclasses, PluralityEliminationEngineProfile and PluralityEliminationEngineProfileUM. This is used to speed up the computation of the winner for RuleExhaustiveBallot, RuleICRV, RuleIRVAverage, IRVDuels and RuleTideman.

0.6.8 (2021-07-27): Accelerate Exhaustive Ballot and some related rules#

  • RuleExhaustiveBallot, RuleCondorcetAbsIRV and RuleCondorcetVtbIRV: accelerate counting the ballots. This also speeds up RuleIRV, which relies directly on RuleExhaustiveBallot.

0.6.7 (2021-07-27): Accelerations#

  • The option sort_voters in Profile and related classes (such as GeneratorProfile and its subclasses) is now False by default.

  • Rule: accelerate exact IM, UM and CM (generic exact algorithms for ranking-based rules).

  • RuleBaldwin: accelerate counting the ballot and computing the winner (especially useful for exact UM).

  • RuleSTAR: accelerate TM.

  • RuleICRV, RuleIRVAverage, RuleSmithIRV, RuleTideman, RuleWoodall: accelerate CM.

  • Improve the management of options in RuleExhaustiveBallot and RuleIRV. In some (common) cases, it accelerates the computation of related voting rules (RuleCondorcetAbsIRV, etc).

0.6.6 (2021-07-27): Fix bug in ProfileUM#

  • Fix bug: preferences_rk was an array of floats, it is now an array of integers.

0.6.5 (2021-07-27): Accelerations#

  • Accelerate ProfileSubsetCandidates (used for IIA but also for some voting rules such as RuleTideman).

  • Add ProfileUM. This is used to speed up the generic exact algorithm for UM in the case of voting rules based on rankings.

  • RuleTideman: accelerate counting the ballot and computing the winner (especially useful for exact UM).

  • Accelerate preferences_ut_to_matrix_duels_ut.

  • Accelerate matrix_victories_to_smith_set.

0.6.4 (2021-07-27): Option “faster” for Maximin#

  • RuleMaximin: implement cm_option=faster, which is as precise as fast to compute is_cm_, less precise to compute the bounds necessary_coalition_size_cm_ and sufficient_coalition_size_cm_, but a lot faster.

0.6.3 (2021-07-27): Accelerate ProfileSubsetCandidates#

  • Profile now has a parameter preferences_borda_rk. At initialization, it can be given instead of preferences_rk.

  • ProfileSubsetCandidates: accelerate the initialization method.

0.6.2 (2021-07-27): Accelerate Maximin#

  • Accelerate RuleMaximin.necessary_coalition_size_cm_ and RuleMaximin.sufficient_coalition_size_cm_.

  • Add RuleMaximin.sufficient_coalition_size_um_c_: number of manipulators that are sufficient (and necessary) for UM.

0.6.1 (2021-07-27): Accelerate Profile#

  • Accelerate Profile: lazy evaluation of attributes preferences_rk, preferences_ut, preferences_borda_rk and preferences_borda_ut. This leads to a very significant acceleration for many methods (typically TM, UM and IIA, but also CM and IM for some voting rules).

0.6.0 (2021-07-26): ExperimentsCompiler#

  • Add ExperimentsCompiler: draw plots and prepare tables based on the results computed by ExperimentAnalyzer on several experiments.

  • Accelerate RuleMajorityJudgment.necessary_coalition_size_cm_ and RuleMajorityJudgment.sufficient_coalition_size_cm_.

0.5.1 (2021-07-24): Fix PyPI deployment#

  • Fix PyPI deployment.

0.5.0 (2021-07-24): Meta#

  • This release focuses on “meta” tools that make the simulations easier.

    • Add StudyProfileCriteria: a set of criteria to study for the simulator about the profiles.

    • Add StudyRuleCriteria: a set of criteria to study for the simulator about one or several voting rules.

    • Add VotingRuleTasks: a set of tasks for the simulator, i.e. which voting rules with which options and which criteria about them.

    • Add ExperimentAnalyzer: a simulator designed to study small variations of a given profile.

  • New features for Rule:

    • Add check_option_allowed: check whether a pair (option, value) is allowed.

    • Add cm_power_index_: CM power index.

    • Add elects_condorcet_winner_rk_even_with_cm_: True if there is a Condorcet winner, she is elected by sincere voting and it is not CM.

    • Add is_tm_or_um_: True iff the profile is TM or UM.

    • Add log_: log corresponding to a particular manipulation method.

    • Add nb_candidates_cm_: number of candidates who can benefit from CM.

    • Add relative_social_welfare_w_: relative social welfare of the winner.

    • Add worst_relative_welfare_with_cm_: worst relative social welfare (sincere winner or candidate who can benefit from CM).

    • Each rule now has two class attributes full_name (name of the rule) and abbreviation (abbreviation of the name of the rule). For example, for RuleApproval, it is Approval Voting and AV respectively.

    • options_parameters is now a class attribute.

    • Accelerate the generic brute-force algorithm for exact UM when the rule is based on rankings.

  • New features for Profile:

    • Add property relative_social_welfare_c: relative social welfare of each candidate.

    • preferences_rk, preferences_ut, preferences_borda_rk and preferences_borda_ut are now properties.

  • Minor changes:

    • GeneratorProfile and all its subclasses now have a parameter sort_voters, which is simply passed to Profile when creating each profile.

    • ProfileGeneratorNoisedFile is renamed to GeneratorProfileNoisedFile, for the sake of consistency with other profile generators.

    • RULE_CLASSES is renamed to ALL_RULE_CLASSES.

    • Add utility functions indent and pseudo_bool_not.

0.4.3 (2021-07-21): Accelerations#

  • Rule: accelerate trivial manipulation (TM) for rules based on rankings.

  • Profile: compute preferences_borda_ut only when needed. In particular, if often accelerates trivial manipulation (which relies on examining an alternate Profile object, with trivial strategy for manipulators).

  • RuleMajorityJudgment, RuleRangeVoting and RuleSTAR: accelerate the computation of the ballots.

0.4.2 (2021-07-20): Accelerate plurality_scores_ut#

  • Accelerate Profile.plurality_scores_ut. As an example, for a profile with 65,000 voters and 5 candidates, the new version is approximately 10 times faster.

0.4.1 (2021-07-20): Fix Missing Subpackage in Deployment#

  • Fix bug: in some distributions, some subpackages of Svvamp were not included.

0.4.0 (2021-07-19): Black, Copeland, Split Cycle, STAR#

  • Add RuleBlack.

  • Add RuleCopeland.

  • Add RuleSplitCycle.

  • Add RuleSTAR.

  • In RuleRangeVoting and RuleMajorityJudgment, add an attribute allowed_grades: a list of the allowed grades.

0.3.0 (2021-07-16): New CM Algorithms for Smith-IRV-Like Rules#

  • New CM algorithms for Smith-IRV-like rules:

    • New CM algorithms for RuleICRV, RuleSmithIRV, RuleTideman, RuleWoodall and RuleIRVAverage.

    • Add RuleIRV.example_ballots_cm_c_ and RuleIRV.example_ballots_cm_w_against_: examples of manipulating ballots (used as heuristic to manipulate Smith-IRV and similar rules).

    • In RuleCondorcetAbsIRV and RuleCondorcetVtbIRV, the former option almost_exact is renamed to very_slow, for the sake of consistency with Smith-IRV and similar voting rules.

  • Improve imports/exports:

    • ProfileFromFile can now import a CVR (cast vote record) file.

    • ProfileFromFile has a new parameter sort_candidates: sort the candidates from strongest to weakest (in a Black method sense).

    • Add Profile.to_csv: export the utilities to a csv file.

  • Add Rule.options: a dictionary with all the options of a rule.

  • Bug fixes:

    • Fix a major bug in RuleTideman: ballots were not counted correctly.

    • Fix a bug in RuleExhaustiveBallot and RuleIRV: applying a voting rule to a profile was able to change the options of another (related) rule.

0.2.0 (2021-07-13): Smith-IRV and Similar Voting Rules#

  • A Profile object can now compute its Smith set (also called “top cycle”): smith_set_rk, smith_set_rk_ctb, smith_set_ut_abs, smith_set_ut_abs_ctb, smith_set_ut_rel, smith_set_ut_rel_ctb.

  • Add Smith-IRV.

  • Add Tideman’s rule.

  • Add Woodall’s rule.

  • Add constant RULE_CLASSES: list of all the rule classes.

  • Tools that are mostly dedicated to developers:

    • A global option allows to throw an error when an uncovered portion of code is reached.

    • Add Profile.to_doctest_string.

    • Add Rule._set_random_options.

    • Add Rule._random_instruction.

0.1.2 (2021-07-12): Fix Release Number#

  • Fix release number.

0.1.1 (2021-07-12): Fix Deployment#

  • Fix deployment on PyPI.

0.1.0 (2021-07-12): Complete Refactoring#

  • Refactor the code completely. New architecture, especially for Rule (formerly Election), avoiding diamond inheritance. Rename most classes, properties and methods.

  • Cover the code with tests. Print a message when execution reaches an uncovered part of the code.

  • Fix some minor bugs.

  • Documentation in numpy style.

  • Tutorials are now Jupyter notebooks.

  • New rules: Kim-Roush and IRV-Average.

0.0.4 (2015-03-10): Fix a Bug in Plurality#

  • Correct a minor bug in Plurality.IM (voters_IM is now updated).

0.0.3 (2015-02-28): Miscellaneous Minor Improvements#

  • Rename functions and attributes with suffix _vtb to _rk.

  • Allow to define a population by both utilities and rankings.

  • Add shift to Euclidean box model.

  • Range voting / Majority Judgment: with a discrete set of grades, send to closest authorized grades.

0.0.2 (2015-02-16): SVVAMP’s Core Features#

  • 8 population models and 23 voting systems.

0.0.1 (2015-02-14): First Release#

  • First release on PyPI.