Complex sentence: Louis XIV formally decreed the Paris Opéra a permanent company for dance in 1713, also creating an associated ballet school to study dance, today known as the Paris Opera Ballet School.
Split into simpler sentences: Louis XIV formally decreed the Paris Opéra a permanent company for dance in 1713, also creating an associated ballet school to study dance. In 1713 an associated ballet school was opened, today known as the Paris Opera Ballet School.