Finnish conductor and music director of Ensemble InterContemporain Susanna Malkki pays tribute to Stockhausen's 1950s masterpiece Gruppen for 3 orchestras, and highlights some of the challenges to conductors in performing it; commentator Paul Griffiths places the work in the context of Stockhausen's early output, and explains how the shape of a mountain view in Switzerland dictated the work's tempo patterns. Show less