“Mr. Abramov’s people are ordinary-looking middle-aged Russian women in cloth coats, and their expressions are all business. They assemble on the stairs, and as the first curtain approaches, they break up into formations, like synchronized swimmers, and vanish into the stream of people heading to their seats. … [Abramov’s] job is to engineer applause and ovations, on the basis of secret agreements with dancers, using associates planted in the audience.”