Dodgson voting rule

In the Dodgson rule the election is modified as least as possible in order to obtain a Condorcet winner. This minimality of change is defined as the minimal number of swaps of adjacent candidates, such that there is a Condorcet winner.


Consider the following example which does not have a Condorcet winner.

1: apple > banana > cherry 2: banana > cherry > apple 3: cherry > apple > banana 4: cherry > banana > apple

Why is there no Condorcet winner?

What happens if you swap the position of the cherries and the banana in the first vote?

Try to evaluate this example on wrt. the Dodgson rule. What can you observe from the output?

Note: In the output, the applied swaps are denoted by swap(vote,from-position, to-position). Each swap accounts 1 cost unit to the optimization value.

Try it out


Status: Idle