SearcharxivSearch

arXiv subjects

Noa Lavi

Publications and source records attributed to Noa Lavi.

5 recordsLinked to original sources

Unique factorization results for generalized power series

Factorization in rings of the form $K((G^{\le 0} )) $ exhibits pathological behavior due to divisibility by monomials. It remains open whether this is the only obstruction and whether the quotient by the ideal generated by all monomials is a unique factorization domain. Prior to this work, the only instances of unique factorization beyond the irreducible elements followed directly from the primality of elements which aren't divisible by any monomial and whose support has order type $\omega$ or $\omega+1$. Using the $RV$ tool from valuation theory as a key ingredient, we establish unique factorization for elements of $ K((\mathbb{R}^{\le 0}))$ which aren't divisible by any monomial and whose support has order type $\omega^{\alpha} $ or $\omega^{\alpha}+1 $ for a large class of non additively principal ordinals $\alpha$.

math.AC

Irreducibility in generalized power series

A classical tool in the study of real closed fields are the fields $K((G))$ of generalized power series (i.e., formal sums with well-ordered support) with coefficients in a field $K$ of characteristic 0 and exponents in an ordered abelian group $G$. In this paper we enlarge the family of ordinals $α$ of non-additively principal Cantor degree for which $K((\mathbb{R}^{\le 0}))$ admits irreducibles of order type $α$ far beyond $α=ω^2 $ and $α= ω^3$ known prior to this work.

math.AC

A Ganzstellensatz for semi-algebraic sets and a boundedness criterion for rational functions

Let $\langle K,ν\rangle$ be a real closed valued field, and let $S\subseteq K^n$ be an open semi-algebraic set. Using tools from model theory, we find an algebraic characterization of rational functions which admit, on $S$, only values in the valuation ring. We use this result to deduce a criterion for a rational function to be bounded on an open semi algebraic subset of some irreducible variety over a real closed field or over an ordered field which is dense in its real closure.

math.AG

Positivstellensätze for semi-algebraic sets in real closed valued fields

The purpose of this paper is to give a characterization for polynomials and rational functions which admit only non-negative values on definable sets in real closed valued fields. That is, generalizing the relative positivstellensätze for sets defined also by valuation terms. For this, we use model theoretic tools, together with existence of canonical valuations.

math.AG