Tragni's method: Difference between revisions

Tragni's method is a [[Single Member system|Single-Winner]] [[Symbolic voting systems]] that uses 2 non-cardinal symbols ( [worst] and [best] ), invented by Aldo Tragni.

With MAX = 5, the proportions range is [1/MAX, MAX] = [1/5, 5]. MAX indicates the highest value that can be used in the cardinal part of the vote.

* If some candidates remain in tie then, using [[Tragni's method#Score_Tragni.27s_Method_.28S-TM.29|S-TM]].

==Strategies resistance==

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! style="width: 150px;" |[[Tactical voting#Pushover|Push-over]]

! style="width: 150px;" |[[Tactical voting#Voting_for_the_lesser_of_two_evils|Voting lesser of two evils]]

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'''[[Tactical voting#Definitions|Min-maxing (benefit)]]''': a voter gives maximal support to some candidates and no support to all other candidates, to benefit those with maximal support (becomes Bullet voting if only 1 candidate has maximal support).

In Tragni's method the voter can give maximal support to a candidate, rating him [best]. The ratings given to the other candidates will not reduce the chances of victory for the rated [best] candidates, therefore the voter is free to show his/her true interests regarding those candidates.

'''[[Tactical voting#Definitions|Min-maxing (disadvantage)]]''': a voter gives maximal support to some candidates and no support to all other candidates, to disadvantage those with no support. It also includes the problem of candidates little known by the voter, who would receive additional support.

In Tragni's method the voter can give minimal support to a candidate, rating him [worst]. The ratings given to the other candidates will not increase the chances of victory for the rated [worst] candidates, therefore the voter is free to show his/her true interests regarding those candidates.

Regarding little-known candidates: if they aren't evaluated, they automatically receive [worst]; if they are evaluated, they will receive the lowest rating, but higher than [worst], that is 1. With this rating, it's practically impossible for a little known candidate to win.

'''[[Tactical voting#Pushover|Push-over]]''': a voter rating an alternative lower in the hope of getting it elected, or rating an alternative higher in the hope of defeating it (concerns only methods that fail monotony).

'''[[Tactical voting#Voting_for_the_lesser_of_two_evils|Voting lesser of two evils]]''': given 2 front runners, a voter gives maximal support to the best one and no support to the worst one.

In Tragni's method, assuming that the 2 front runners have different ratings in the non-strategic vote, then if the worst of the 2 is rated [worst], or if the best is rated [best], or they are rated 1 and 5 respectively, then the vote doesn't change (no strategy); otherwise, the worst of the 2 will be rated [worst]. The one described is the worst case.

''If in the [[Tragni's method#Formula|formula]] to manage the proportions of [worst] and [best], a higher value had been used instead of MAX (like MAX + 1 or MAX * 2), then in the case with the two front runners rated 1 and 5, the worst would have been put to [worst], increasing the damage of this strategy, even if only slightly.''