premise: A museum curator is arranging seven paintings—a Morisot, a Pissarro, a Renoir, a Sisley, a Turner, a Vuillard, and a Whistler. The paintings will be arranged in a horizontal row of seven positions, with the first position being closest to the entrance and the seventh being furthest from the entrance. The arrangement is subject to the following constraints: The Turner must be closer to the entrance than the Whistler is. The Renoir must be closer to the entrance than the Morisot is, with exactly one other painting between them. The Pissarro and the Sisley must be next to each other. If the Vuillard is not in the third position, it must be in the fourth position. If there is exactly one painting between the Turner and the Whistler, which one of the following must be true?
hypothesis: The Vuillard is in the third position.