donna and kim are both administrators for the accounting department. because someone must be present to answer the phones at all times, different times must be scheduled for each of them to go to lunch. both of them want the time from noon to 1 p.m. previous unsuccessful discussions have occurred, resulting in their not speaking to each other. patti, who also works in the department, sits down separately with each of them to try to explore possible solutions, with the idea that if she can find common ground, they will again discuss alternative schedules face-to-face. patti is acting as a(n)