premise: A man wearing a white shirt and a hat, riding his bike, makes an obscene gesture to the photographer. hypothesis: The bike rider and the photographer greeted each other warmly.
contradiction: The bike rider cannot simultaneously make an obscene gesture and have greeted someone warmly.|contradiction: If the bike rider and the photographer are making obscene gestures then they cannot be greeting each other warmly.|contradiction: It doesn't make sense to make an obscene gesture to a person and then greet them warmly.