premise: Exactly seven professors—Madison, Nilsson, Orozco, Paton, Robinson, Sarkis, and Togo—were hired in the years 1989 through 1995. Each professor has one or more specialities, and any two professors hired in the same year or in consecutive years do not have a specialty in common. The professors were hired according to the following conditions: Madison was hired in 1993, Robinson in 1991. There is at least one specialty that Madison, Orozco, and Togo have in common. Nilsson shares a specialty with Robinson. Paton and Sarkis were each hired at least one year before Madison and at least one year after Nilsson. Orozco, who shares a specialty with Sarkis, was hired in 1990. Which one of the following must be true?
hypothesis: Orozco was hired before Paton.