On t-fold blocking sets in affine spaces and the sharpness of Bruenʼs bound

2013 ◽  
Vol 40 ◽  
pp. 329-333
Author(s):  
Ivan Landjev ◽  
Assia Rousseva
Keyword(s):  
1987 ◽  
Vol 28 (2) ◽  
pp. 111-116 ◽  
Author(s):  
Albrecht Beutelspacher ◽  
Francesco Mazzocca

Author(s):  
Chunming Tang ◽  
Yan Qiu ◽  
Qunying Liao ◽  
Zhengchun Zhou

Author(s):  
Cristina Bertone ◽  
Francesca Cioffi

AbstractGiven a finite order ideal $${\mathcal {O}}$$ O in the polynomial ring $$K[x_1,\ldots , x_n]$$ K [ x 1 , … , x n ] over a field K, let $$\partial {\mathcal {O}}$$ ∂ O be the border of $${\mathcal {O}}$$ O and $${\mathcal {P}}_{\mathcal {O}}$$ P O the Pommaret basis of the ideal generated by the terms outside $${\mathcal {O}}$$ O . In the framework of reduction structures introduced by Ceria, Mora, Roggero in 2019, we investigate relations among $$\partial {\mathcal {O}}$$ ∂ O -marked sets (resp. bases) and $${\mathcal {P}}_{\mathcal {O}}$$ P O -marked sets (resp. bases). We prove that a $$\partial {\mathcal {O}}$$ ∂ O -marked set B is a marked basis if and only if the $${\mathcal {P}}_{\mathcal {O}}$$ P O -marked set P contained in B is a marked basis and generates the same ideal as B. Using a functorial description of these marked bases, as a byproduct we obtain that the affine schemes respectively parameterizing $$\partial {\mathcal {O}}$$ ∂ O -marked bases and $${\mathcal {P}}_{\mathcal {O}}$$ P O -marked bases are isomorphic. We are able to describe this isomorphism as a projection that can be explicitly constructed without the use of Gröbner elimination techniques. In particular, we obtain a straightforward embedding of border schemes in affine spaces of lower dimension. Furthermore, we observe that Pommaret marked schemes give an open covering of Hilbert schemes parameterizing 0-dimensional schemes without any group actions. Several examples are given throughout the paper.


1989 ◽  
Vol 35 (1-2) ◽  
pp. 75-86 ◽  
Author(s):  
Mario Gionfriddo ◽  
Biagio Micale
Keyword(s):  

2008 ◽  
Vol 308 (2-3) ◽  
pp. 180-183
Author(s):  
S. Rajola ◽  
M. Scafati Tallini
Keyword(s):  

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