Noether's problem over an algebraically closed field.
Non commutative Krull domains.
Non-axiomatizability of real spectra in
We show that the property of a spectral space, to be a spectral subspace of the real spectrum of a commutative ring, is not expressible in the infinitary first order language of its defining lattice. This generalises a result of Delzell and Madden which says that not every completely normal spectral space is a real spectrum.
Noncoherence of a causal Wiener algebra used in control theory.
Noncommutative del Pezzo surfaces and Calabi-Yau algebras
The hypersurface in with an isolated quasi-homogeneous elliptic singularity of type , has a natural Poisson structure. We show that the family of del Pezzo surfaces of the corresponding type provides a semiuniversal Poisson deformation of that Poisson structure. We also construct a deformation-quantization of the coordinate ring of such a del Pezzo surface. To this end, we first deform the polynomial algebra to a noncommutative algebra with generators and the following 3 relations labelled...
Non-commutative reduction rings.
Noncommutative Valuation Rings
Non-embeddable -convex manifolds
We show that every small resolution of a 3-dimensional terminal hypersurface singularity can occur on a non-embeddable -convex manifold.We give an explicit example of a non-embeddable manifold containing an irreducible exceptional rational curve with normal bundle of type . To this end we study small resolutions of -singularities.
Non-existence of the Artin function for Henselian pairs.
Nonflat deformations of modules and isolated singularities.
Non-free Projective Modules Over IH[X, Y] and Stable Bundles Over IP2(...).
Non-Leibniz algebras with logarithms do not have the trigonometric identity
Let X be a Leibniz algebra with unit e, i.e. an algebra with a right invertible linear operator D satisfying the Leibniz condition: D(xy) = xDy + (Dx)y for x,y belonging to the domain of D. If logarithmic mappings exist in X, then cosine and sine elements C(x) and S(x) defined by means of antilogarithmic mappings satisfy the Trigonometric Identity, i.e. whenever x belongs to the domain of these mappings. The following question arises: Do there exist non-Leibniz algebras with logarithms such that...
Non-Noetherian Rings for which Each Proper Subring is Noetherian.
Non-transitive generalizations of subdirect products of linearly ordered rings
Weakly associative lattice rings (wal-rings) are non-transitive generalizations of lattice ordered rings (l-rings). As is known, the class of l-rings which are subdirect products of linearly ordered rings (i.e. the class of f-rings) plays an important role in the theory of l-rings. In the paper, the classes of wal-rings representable as subdirect products of to-rings and ao-rings (both being non-transitive generalizations of the class of f-rings) are characterized and the class of wal-rings having...
Non-unique factorizations in orders of global fields.
Normability of an S-ring.
We give some criteria of normability of an S-ring, and we study the properties of its norms.
Normal and tangential flatness.
Normal bases for infinite Galois ring extensions
Normal polytopes, triangulations, and Koszul algebras.
Normal rings and local ideals.