A rational map empty set : P-k(m) ---> P-k(n) is defined by homogeneous polynomials of a common degree d. We establish a linear bound in terms of d for the number of (m - 1)-dimensional fibers of empty set, by using ideals of minors of the Jacobian matrix. In particular, we answer affirmatively Question 11 in [9]. (C) 2019 Elsevier Inc. All rights reserved.
机构:
Laboratory of Quantitative Vegetation Ecology, Institute of Botany, Chinese Academy of SciencesLaboratory of Quantitative Vegetation Ecology, Institute of Botany, Chinese Academy of Sciences