premise: A young man in a blue hoodie doing a flip off of a half-wall that is covered in graffiti. hypothesis: A young man in a blue hoodie falls off a half-wall that is painted nicely.
contradiction: If a young man is doing a flip off of a half-wall, he cannot fall off of it. If the half-wall is covered in graffiti, it cannot be painted nicely.|contradiction: The wall is painted in graffiti which is not considered a nice paint.  Therefore the walls are not the same.|contradiction: Is the boys doing a flip then he did not fall in the wall can either be covered in graffiti or nicely painted not both.