Need for article

 Barbara, 

When used in a structure like this, French possessive pronouns are unusual in that they include a ‘definite’ article ( le, la, les ) in 2-part structures, agreeing in gender and number with the noun replaced. 

Hence there is a compulsory contraction of ‘ à le ‘ to ‘ au ‘, in the sentence -  ‘ inférieur (à le) nôtre ‘ to ‘ inférieur au nôtre ‘.  

This can be seen if you ‘ produit ‘ with a feminine singular noun and use a possessive pronoun

That car is inferior to ours - Cette voiture est inférieure à la nôtre 

https://www.wordreference.com/enfr/mine

 Le nôtre/le vôtre/le leur/etc = Ours/yours/theirs (French Possessive Pronouns)

Le mien/le tien/le sien/etc = Mine/yours/his/hers/its (French Possessive Pronouns)

 https://www.larousse.fr/dictionnaires/francais/n%C3%B4tre/55077