2008/05/05 by Averkov, Gennadiy
#14P10 #52B05 #Algebraic Geometry (math.AG) #FOS: Mathematics #Metric Geometry (math.MG)
paper · doi:10.48550/arxiv.0805.0522
Consider a semi-algebraic set A in Rd constructed from the sets which are determined by inequalities pi(x)>0, pi(x)≥ 0, or pi(x)=0 for a given list of polynomials p1,...,pm. We prove several statements that fit into the following template. Assume that in a neighborhood of a boundary point the semi-algebraic set A can be described by an irreducible polynomial f. Then f is a factor of a certain multiplicity of some of the polynomials p1,...,pm. Special cases when A is elementary closed, elementary open, a polygon, or a polytope are considered separately.