scholarly journals The weak Lefschetz property and powers of linear forms in $\mathbb {K}[x,y,z]$

2010 ◽  
Vol 138 (07) ◽  
pp. 2335-2335 ◽  
Author(s):  
Hal Schenck ◽  
Alexandra Seceleanu
2012 ◽  
Vol 6 (3) ◽  
pp. 487-526 ◽  
Author(s):  
Juan C. Migliore ◽  
Rosa M. Miró-Roig ◽  
Uwe Nagel

2018 ◽  
Vol 30 (4) ◽  
pp. 857-865 ◽  
Author(s):  
Charles Almeida ◽  
Aline V. Andrade

Abstract In [9], Migliore, Miró-Roig and Nagel proved that if {R=\mathbb{K}[x,y,z]} , where {\mathbb{K}} is a field of characteristic zero, and {I=(L_{1}^{a_{1}},\dots,L_{4}^{a_{4}})} is an ideal generated by powers of four general linear forms, then the multiplication by the square {L^{2}} of a general linear form L induces a homomorphism of maximal rank in any graded component of {R/I} . More recently, Migliore and Miró-Roig proved in [7] that the same is true for any number of general linear forms, as long the powers are uniform. In addition, they conjectured that the same holds for arbitrary powers. In this paper, we will prove that this conjecture is true, that is, we will show that if {I=(L_{1}^{a_{1}},\dots,L_{r}^{a_{r}})} is an ideal of R generated by arbitrary powers of any set of general linear forms, then the multiplication by the square {L^{2}} of a general linear form L induces a homomorphism of maximal rank in any graded component of {R/I} .


2021 ◽  
Vol 568 ◽  
pp. 22-34
Author(s):  
Gioia Failla ◽  
Zachary Flores ◽  
Chris Peterson

Algebra ◽  
2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Edoardo Ballico ◽  
Alessandra Bernardi

We study the case of a real homogeneous polynomial whose minimal real and complex decompositions in terms of powers of linear forms are different. We prove that if the sum of the complex and the real ranks of is at most , then the difference of the two decompositions is completely determined either on a line or on a conic or two disjoint lines.


2008 ◽  
Vol 60 (2) ◽  
pp. 391-411 ◽  
Author(s):  
Juan C. Migliore

AbstractIn a recent paper, F. Zanello showed that level Artinian algebras in 3 variables can fail to have the Weak Lefschetz Property (WLP), and can even fail to have unimodal Hilbert function. We show that the same is true for the Artinian reduction of reduced, level sets of points in projective 3-space. Our main goal is to begin an understanding of how the geometry of a set of points can prevent its Artinian reduction from having WLP, which in itself is a very algebraic notion. More precisely, we produce level sets of points whose Artinian reductions have socle types 3 and 4 and arbitrary socle degree ≥ 12 (in the worst case), but fail to have WLP. We also produce a level set of points whose Artinian reduction fails to have unimodal Hilbert function; our example is based on Zanello's example. Finally, we show that a level set of points can have Artinian reduction that has WLP but fails to have the Strong Lefschetz Property. While our constructions are all based on basic double G-linkage, the implementations use very different methods.


1933 ◽  
Vol 29 (4) ◽  
pp. 465-469 ◽  
Author(s):  
J. Bronowski

1. In a recent paper I established new conditions for a form φ of order n, homogeneous in r + 1 variables, to be expressible as the sum of nth powers of linear forms in these variables; and for this expression, if it exists, to be unique. These conditions, I further showed, may be stated as general theorems regarding the secant spaces of manifolds Mr in higher space, namely:Necessary and sufficient conditions that through a general point of a space N, of h (r + 1) − 1 dimensions, there passes (i) no, (ii) a unique (h − 1)-dimensional space containing h points of a manifold Mr lying in N are that(i) the space projecting a general point of Mr from the join of h − 1 general r-dimensional tangent spaces of Mr meets Mr in a curve, so that Mr cannot be so projected upon a linear space of r dimensions;(ii) the space projecting a general point of Mr from the join of h − 1 general r-dimensional tangent spaces of Mr does not meet Mr again, so that Mr can be so projected, birationally, upon a linear space of r dimensions..


Geometry ◽  
2013 ◽  
Vol 2013 ◽  
pp. 1-2 ◽  
Author(s):  
E. Ballico

Fix integers m≥5 and d≥3. Let f be a degree d homogeneous polynomial in m+1 variables. Here, we prove that f is the sum of at most d·⌈(m+dm)/(m+1)⌉d-powers of linear forms (of course, this inequality is nontrivial only if m≫d.)


1949 ◽  
Vol 50 (3) ◽  
pp. 691 ◽  
Author(s):  
R. A. Rankin

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