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When is a Polynomial Ideal Binomial After an Ambient Automorphism?
Foundations of Computational Mathematics ( IF 3 ) Pub Date : 2018-11-12 , DOI: 10.1007/s10208-018-9405-0
Lukas Katthän , Mateusz Michałek , Ezra Miller

Can an ideal I in a polynomial ring \(\Bbbk [\mathbf {x}]\) over a field be moved by a change of coordinates into a position where it is generated by binomials \(\mathbf {x}^\mathbb A- \lambda \mathbf {x}^\mathbf {b}\) with \(\lambda \in \Bbbk \), or by unital binomials (i.e., with \(\lambda = 0\) or 1)? Can a variety be moved into a position where it is toric? By fibering the G-translates of I over an algebraic group G acting on affine space, these problems are special cases of questions about a family \(\mathcal {I}\) of ideals over an arbitrary base B. The main results in this general setting are algorithms to find the locus of points in B over which the fiber of \(\mathcal {I}\)
  • is contained in the fiber of a second family \(\mathcal {I}'\) of ideals over B;
  • defines a variety of dimension at least d;
  • is generated by binomials; or
  • is generated by unital binomials.
A faster containment algorithm is also presented when the fibers of \(\mathcal {I}\) are prime. The big-fiber algorithm is probabilistic but likely faster than known deterministic ones. Applications include the setting where a second group T acts on affine space, in addition to G, in which case algorithms compute the set of G-translates of I
  • whose stabilizer subgroups in T have maximal dimension; or
  • that admit a faithful multigrading by \(\mathbb {Z}^r\) of maximal rank r.
Even with no ambient group action given, the final application is an algorithm to
  • decide whether a normal projective variety is abstractly toric.
All of these loci in B and subsets of G are constructible.


中文翻译:

自环境同态后的多项式理想二项式是什么时候?

多项式环\(\ Bbbk [\ mathbf {x}] \)中的理想 I是否可以通过更改坐标而移动到二项式\(\ mathbf {x} ^ \ mathbb生成位置的位置A- \ lambda \ mathbf {x} ^ \ mathbf {b} \)\(\ lambda \ in \ Bbbk \)或单位二项式(即\(\ lambda = 0 \)或1)?品种可以移到复曲面的位置吗?通过fibering的的-translates 了代数群 作用于仿射空间,这些问题都是关于家庭问题的特殊情况 \(\ mathcal {I} \)在任意基地的理想 。在此一般设置下的主要结果是找到\(\ mathcal {I} \)的光纤 在B中的点的轨迹的算法 
  • 被包含在第二个家庭的纤维 \(\ mathcal {I}'\)超过理想的 ;
  • 至少定义d的各种尺寸 ;
  • 由二项式生成;要么
  • 由单位二项式生成。
\(\ mathcal {I} \)的纤维为素数时,还提出了一种更快的遏制算法 。大光纤算法是概率性的,但可能比已知的确定性算法更快。应用包括其中第二组的设定 Ť作用在仿射空间中,除了 G ^,在这种情况下的算法计算所述一组ģ的-translates 
  • T中的稳定剂亚组 具有最大尺寸;要么
  • 接受最大等级r\(\ mathbb {Z} ^ r \)的 忠实多重评分 。
即使没有给出环境小组动作,最终的应用程序还是
  • 确定正常的投影变种是否抽象复曲面。
B中的所有这些基因座 和G的子集 都是可构建的。
更新日期:2018-11-12
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