context: A man dressed in a surfing shirt and blue and white shorts skillfully guides his yellow board with its multicolored sail over the crest of an ocean wave, flipping over in the process.
hypothesis: It is certain that a man has surfed for an hour
valid_hypothesis: It is unlikely that a man has surfed for an hour
invalid_hypothesis: It is certain that a man has surfed for an hour
hypothesis_assertion: a man has surfed for an hour