The DH3 "Dark Horse plus 3 rivals" pathology (Executive summary)
Many voting system "pathologies" or "paradoxes" or "bad behaviors"
have been noticed over the years.
The most damaging ones are those that occur often
and which lead to very serious problems such as election of
the winner unanimously agreed to be worst.
The DH3 pathology is horribly (near-maximally) common and horribly (maximally in the
4-candidate case) severe.
It devastates both the Borda voting system and all Condorcet systems
based on full rank orderings as votes.
This illustrates the extremely severe reaction
("anaphylactic shock") of these systems to "strategic voters."
But range voting reacts only mildly to strategic voters.
In the DH3
scenario, Range has no problem and just elects the best winner.