In San Francisco,"majority" is of the "continuing" ballots, not a majority of all ballots:
"If no candidate receives a majority of votes from the continuing ballots after a candidate has been eliminated and his or her votes have been transferred to the next-ranked candidate, the continuing candidate with the fewest votes from the continuing ballots shall be eliminated. All votes cast for that candidate shall be transferred to the next-ranked continuing candidate on each voter's ballot. This process of eliminating candidates and transferring their votes to the next-ranked continuing candidates shall be repeated until a candidate receives a majority of the votes from the continuing ballots." SEC. 13.102. - INSTANT RUNOFF ELECTIONS.(D) go to this link and type in the SEC. 13.102 in search box. Amended in March 2002.
In other words, the majority consists of the votes left after others are eliminated. The elimination of ballots and the exhaustion of ballots (the point a ballot does not have choices marked) is part of the reason that in many instant runoff voting elections often suffer majority failure.
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