Quiz Stuff

• Use a full sheet of 8½ x 11" paper. (Half sheet? Half credit!)
• Put your last name and first initial in the far upper left hand corner!
  
• No need to write out questions.
• Numbering responses may help you avoid overlooking a question; it's ok to go ahead and pre-number your sheet.
• Time: 3:30; two questions
• Can everybody see this line?

Quiz 9; November 7; 3'30"; 1½ points each

1. Write a predicate second(?List,?Second) that is true iff Second is the second element of List. Examples:

   ?- second([a,b,c],S).
   S = b.
   
   ?- second([a,b,c],10).
   false.
   
   ?- second([a],S).
   false.
   

2. Problems like the pit-crossing puzzle can be solved in Prolog by repeatedly applying a three-step process until a solution is found. Briefly, what are those three steps?