Complex sentence: Dual nationals may compete for either country if three years have passed since the competitor competed for the former country; if the NOCs and IF involved agree, then the IOC Executive Board may reduce or cancel this period.
Split into simpler sentences: Dual nationals may compete for either country, as long as three years have passed since the competitor competed for the former country. However, if the NOCs and IF involved agree, then the IOC Executive Board may reduce or cancel this period.