premise: Five snowmobile riders all wearing helmets and goggles line up in a snowy clearing in a forest in front of their snowmobiles; they are all wearing black snow pants and from left to right they are wearing a black coat, white coat, red coat, blue coat, and black coat. hypothesis: The snowmobile riders are all skydiving.
contradiction: The snowmobile riders either are all skydiving, or line up in a snowy clearing in a forest, but not doing both at once.