question:  What role does Doc play in conjunction with Sandra?
context: [Transcriber's Note: This etext was produced from Worlds of If Science Fiction, May 1962. The many clocks, bedside table size, would have struck a familiar note except that they had little red flags and wheels sprinkled over their faces and they were all in pairs, two clocks to a case. 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. Samples: "They say the Machine has been programmed to play nothing but pure Barcza System and Indian Defenses—and the Dragon Formation if anyone pushes the King Pawn." "I heard the Russians have been programmed—with hypnotic cramming and somno-briefing. 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. "Confidentially, Doc, I was having trouble swallowing ... "Yes, Doc, but...." Doc's ability to interpret her mind was as comforting as the bubbly, mildly astringent mixture she was sipping. What the Machine can do is examine all the likely lines of play for about eight moves ahead—that is, four moves each for White and Black—and then decide which is the best move on the basis of capturing enemy pieces, working toward checkmate, establishing a powerful central position and so on." The Machine is probably programmed to recognize such situations and do something of the same sort, though we can't be sure from the information World Business Machines has released. The equivalent of those in the Machine is the directions fed into it before it plays a game." Flesh-and-blood chess masters have lost games by blunders they could have avoided by looking only one or two moves ahead. Once again, you see, you have the human factor, in this case working for the Machine."
output:  He explains to Sandra how the chess machine works and what the significance of each human chess player is.
options:  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.