premise: Seven librarians—Flynn, Gomez, Hill, Kitson, Leung, Moore, and Zahn—are being scheduled for desk duty for one week—Monday through Saturday. The librarians will be on duty exactly one day each. On each day except Saturday, there will be exactly one librarian on duty, with two on duty on Saturday, subject to the following constraints: Hill must be on desk duty earlier in the week than Leung. Both Hill and Moore must be on desk duty earlier in the week than Gomez. Flynn must be on desk duty earlier in the week than both Kitson and Moore. Kitson must be on desk duty earlier in the week than Zahn. Unless Leung is on desk duty on Saturday, Leung must be on desk duty earlier in the week than Flynn. Which one of the following CANNOT be on desk duty on Tuesday?
hypothesis: Zahn