
Anglais
Let ZI be the free abelian group with basis I, let χ be a pair of integral bilinear forms on ZI. We will endow the free K-algebra K⟨I⟩ generated by I with a comultiplication which depends on χ. This yields an associated bilinear form on K⟨I⟩ which may be called the Drinfeld form. We are going to show that certain elements of K⟨I⟩ which are similar to the well-known quantum Serre relations belong to the left radical of the Drinfeld form, provided certain integrality conditions are satisfied.