Experts swear that it takes a lifetime to learn all the subtleties of the corrida, or fiesta brava, as the bullfight is known in Spain.
Experts explain that bullfighting is relatively easy to understand and master. 
mnli hypothesis: Experts explain that bullfighting is relatively easy to understand and master.  premise: Experts swear that it takes a lifetime to learn all the subtleties of the corrida, or fiesta brava, as the bullfight is known in Spain.