Complex sentence: It was the 81st running of the Prix de l'Arc de Triomphe and was won by Marienbard, ridden by Frankie Dettori and trained by Saeed bin Suroor.
Split into simpler sentences: It was the 81st running of the Prix de l'Arc de Triomphe, and it was won by Marienbard. The winner was ridden by Frankie Dettori and trained by Saeed bin Suroor.