Because
type: WorkPerformance
choir: http://data.carnegiehall.org/names/59918
director: http://data.carnegiehall.org/names/59919
piano: http://data.carnegiehall.org/names/6721
performer: http://data.carnegiehall.org/names/6721
performer: http://data.carnegiehall.org/names/59919
performer: http://data.carnegiehall.org/names/59918
work performed: http://data.carnegiehall.org/works/24098