A troika will take over musical leadership of the St. Paul Chamber Orchestra in the fall of 1988. To be called "an artistic commission," the troika will comprise conductors Christopher Hogwood and Hugh Wolff (whose titles will be director of music and principal conductor, respectively), and composer John Adams, to be dubbed "creative chair." According to Deborah Borda, president and managing director of the ensemble, the three commissioners will confer on matters of programming and artists. For 1987-88, Stanislaw Skrowaczewski will continue to serve as music adviser to the orchestra, with Enrique Arturo Diemecke holding the post of resident conductor. Former music director Pinchas Zukerman stepped down in June "to resume his international recital and concert career" as a violinist.