 What role does Doc play in conjunction with Sandra?
Her last assignment had been to interview the pilot pair riding the first American manned circum-lunar satellite—and the five alternate pairs who hadn't made the flight. Sandra's chief difficulty was that she knew absolutely nothing about the game of chess—a point that she had slid over in conferring with the powers at the Space Mirror , but that now had begun to weigh on her. Once again, you see, you have the human factor, in this case working for the Machine." Jandorf seized Doc's new demitasse, drained it, set it back on the tray with a flourish and drew himself up. While Sandra arranged for an interview with Jandorf after the day's playing session, Doc reordered his coffee.
 He explains to Sandra how the chess machine works and what the significance of each human chess player is.
 He explains to Sandra that living human personality is key for beating the machine.  He shows Sandra around the tournament.  He explains to Sandra how the chess machine works and what the significance of each human chess player is.  He explains the history of chess scandals to Sandra.