Possible Clues:

• Who “alone has looked on Beauty bare,” according to Edna St. Vincent Millay
• Setter clued puzzle for mathematician
• Greek mathematician, the 'father of geometry'
• Ancient Greece’s “father of geometry”
• Signal over top mathematician
• Signal sent back by top Greek mathematician
• So-called 'father of geometry'
• Suggestion upset top mathematician
• Great Greek geometer
• Greek mathematician, 50, in Brussels police department