premise: The manager of a photography business must assign at least two photographers to each of two graduation ceremonies—one at Silva University and the other at Thorne University. Exactly six photographers are available—Frost, Gonzalez, Heideck, Knutson, Lai, and Mays—but not all have to be assigned. No photographer can be assigned to both ceremonies. The following constraints apply: Frost must be assigned together with Heideck to one of the graduation ceremonies. If Lai and Mays are both assigned, it must be to different ceremonies. If Gonzalez is assigned to the Silva University ceremony, then Lai must be assigned to the Thorne University ceremony. If Knutson is not assigned to the Thorne University ceremony, then both Heideck and Mays must be assigned to it. Which one of the following is a complete and accurate list of all of the photographers who must be assigned?
hypothesis: Frost, Heideck, Knutson