premise: A woman teaching a ballet class composed of small children holding colourful scarves. hypothesis: A woman is teaching a ballet class composed of middle aged men holding white scarves.
contradiction: Small children cannot also be middle aged men.  White scarves cannot also be colorful.|contradiction: The same woman cannot teach both ballet class because one had small children with colorful scarves and the other has middle aged men with white scarves.|contradiction: Children are not men.