English

A local to global question for linear functionals

Algebraic Geometry 2024-02-19 v1

Abstract

Let FF be an algebraically closed field and let n3n\geq 3. Consider V=FnV=F^n with standard basis {e1,,en}\{\vec{e}_1,\ldots,\vec{e}_n\} and its dual space V=HomFlin(V,F)V^*= {\mathrm{Hom}}_{F-{\mathrm{lin}}}(V,F) with dual basis {y1,,yn}V\{y_1,\ldots,y_n\}\subseteq V^* and let y=iyieiVV\vec{y} = \sum_i y_i\otimes \vec{e}_i\in V^*\otimes V. Let d<nd<n and consider the vectors q1,,qdVV\vec{q}_1,\ldots,\vec{q}_d\in V^*\otimes V. In this note we consider the question of whether y(v)=vSpanF(q1(v),,qd(v))\vec{y}(\vec{v}) = \vec{v} \in Span_F(\vec{q}_1(\vec{v}),\ldots,\vec{q}_d(\vec{v})) for all vV\vec{v}\in V implies that ySpanF(q1,,qd)\vec{y}\in Span_F(\vec{q}_1,\ldots,\vec{q}_d). We show this is true for d=1d=1 or d=2d=2, but that additional properties are needed for d3d\geq 3. We then interpret this result in terms of subspaces of Mn(F)M_n(F) that do not contain any rank 1 idempotents.

Cite

@article{arxiv.2402.10378,
  title  = {A local to global question for linear functionals},
  author = {George F. Seelinger and Wenhua Zhao},
  journal= {arXiv preprint arXiv:2402.10378},
  year   = {2024}
}

Comments

12 pages

R2 v1 2026-06-28T14:50:15.168Z