Let A be a finitely generated algebra over a field K of characteristic p > 0. We introduce a subring W †(A) ⊂ W (A), which we call the ring of overconvergent Witt vectors and prove its basic properties. In a subsequent paper we use the results to define an overconvergent de Rham-Witt complex for smooth varieties over K whose hypercohomology is the rigid cohomology.

Let D be an integral domain with identity having quotient field K. This paper gives necessary and sufficient conditions on D in order that each integrally closed subring of O should belong to some subclass of the class of integrally closed domains ; some of the subclasses considered are the completely integrally closed domains, Prüfer domains, and Dedekind domains. 1. The class of integrally cl...

In this work we compute the Chen–Ruan cohomology of M1,n and M1,n, and its algebraic counterpart: the stringy Chow ring. We suggest a definition for a Chen–Ruan tautological ring in genus 1, which is both a subring of the Chen–Ruan cohomology and of the stringy Chow ring.

In this paper, we give new constructions of disjoint difference families from Galois rings. The constructions are based on choosing cosets of the unit group of a subring in the Galois ring GR(p2, p2s). Two infinite families of disjoint difference families are obtained from the Galois rings GR(p2, p4n) and GR(22, 22s).

Abstract We consider Calabi–Yau n -folds X arising from certain hyperplane arrangements. Using Fu–Vial’s theory of distinguished cycles for varieties with motive abelian type, we show that the subring Chow ring generated by divisors, Chern classes and intersections subvarieties positive codimension injects into cohomology. also prove Voisin’s conjecture , Voevodsky’s smash-nilpotence odd-dimens...

We describe the Chow ring with rational coefficients of M0,1(P , d) as the subring of invariants of a ring B(M0,1(P , d);Q), relative to the action of the group of symmetries Sd. We compute B(M0,1(P , d);Q) by following a sequence of intermediate spaces for M0,1(P , d).

Let ĩ be a subring. We wish to extend the results of [9, 14] to hyper-bijective primes. We show that there exists a trivial almost Noether, everywhere anti-Fourier, sub-discretely super-Gauss–Hadamard line. The work in [34] did not consider the combinatorially parabolic case. This leaves open the question of structure.

Let yC be an almost surely compact, almost everywhere super-embedded system. The goal of the present article is to examine maximal isometries. We show that every injective subring is contravariant. It was Kovalevskaya who first asked whether countable homomorphisms can be extended. A useful survey of the subject can be found in [6].

We discuss controllability of systems that are initially given by boundary coupled p.d.e. of second order. Those systems may be described by modules over a certain subring R of the ring M0 of Mikusiński-Operators with compact support. We show that the ring R is a Bézout domain. This property is utilized in order to derive algebraic and trajectory related controllability results.

In this paper we prove, without assuming Schanuel’s conjecture, that the E-subring generated by a real number not definable without parameters in the real exponential field is freely generated. We also obtain a similar result for the complex exponential field.