context: Several firemen stand or sit on a gray roof while working.
hypothesis: It is improbable that several fireman are putting out a fire on a gray roof.
valid_hypothesis: It is likely that several fireman are putting out a fire on a gray roof.
invalid_hypothesis: It is improbable that several fireman are putting out a fire on a gray roof.
hypothesis_assertion: Several fireman are putting out a fire on a gray roof.