Text: The choice of a new puck lead to an uncontrolled development of a 'black league' - illegal games, where neither the players, nor the referees or the audience wore protective masks, and where the probability of infection in poorly-ventilated rooms varied between 0.75 and 0.79 to one.
Entailment: In the 'black league' nobody present wore a protective mask.
Contradiction: The 'black league' was legal and everyone would wear protective masks to be safe.