Originality of thought and method in West African Islamic teaching: a Fulfulde example

African Studies Center Working Paper No. 3

On superheight conditions for the affineness of open subsets

In this paper we consider the open complement U of a hypersurface Y=V(a) in an affine scheme X. We study the relations between the affineness of U, the intersection of Y with closed subschemes, the property that every closed surface in U is affine, the property that every analytic closed surface is Stein and the superheight of the defining ideal a.Comment: 20 page

Lifting chains of prime ideals

We give an elementary proof that for a ring homomorphism A -> B, satisfying the property that every ideal in A is contracted from B, the following property holds: for every chain of prime ideals p_0 \subset ... \subset p_r in A there exists a chain of prime ideals q_0 \subset ... \subset q_r in B such that q_i \cap A = p_i.Comment: to appear in Journal of pure and applied algebr