context: It is impossible that Bernhard is white. It is certain that Brian is gray. Chances are about even that Greg is a swan.
hypothesis: It is impossible that either Greg is a swan, or Brian is gray.
valid_hypothesis: Chances are about even that either Greg is a swan, or Brian is gray.
invalid_hypothesis: It is impossible that either Greg is a swan, or Brian is gray.
hypothesis_assertion: Either Greg is a swan, or Brian is gray.