Results 31 to 40 of about 868 (134)

Tangent cones at infinity

Let $X\subset\mathbb{C}^m$ be an unbounded pure $k$-dimensional algebraic set. We define the tangent cones $C_{4, \infty}(X)$ and $C_{5,\infty}(X)$ of $X$ at infinity. We establish some of their properties and relations. We prove that $X$ must be an affine linear subspace of $\mathbb{C}^m$ provided that $C_{5, \infty}(X)$ has pure dimension $k$.
Dias, Luis Renato Gonçalves, Ribeiro, Nilva Rodrigues   +1 more
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On the tangent cones to plurisubharmonic currents

Bulletin des Sciences Mathématiques, 2016
Let \(T\) be a positive plurisubharmonic (\(i\partial\overline\partial T\geq 0\)) or plurisuperharmonic (\(i\partial\overline\partial T\leq 0\)) current on a neighborhood of \(0\) in \({\mathbb C}^n\). One says that \(T\) has a tangent cone at \(0\) if the weak limit of the family of its homothetic currents exists.
Dabbek, Khalifa, Ghiloufi, Noureddine, Hbil, Jawhar   +2 more
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On the Cohen-Macaulay Property for Quadratic Tangent Cones [PDF]

The Electronic Journal of Combinatorics, 2016
Let $H$ be an $n$-generated numerical semigroup such that its tangent cone $\operatorname{gr}_\mathfrak{m} K[H]$ is defined by quadratic relations. We show that if $n<5$ then $\operatorname{gr}_\mathfrak{m} K[H]$ is Cohen-Macaulay, and for $n=5$ we explicitly describe the semigroups $H$ such that $\operatorname{gr}_\mathfrak{m} K[H]$ is not Cohen ...
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A CANAL SURFACE CONTAINING FOUR STRAIGHT LINES

Journal of Industrial Design and Engineering Graphics
A canal surface is the envelope of spheres with centers traversing a spatial curve called spine curve. The spheres contact the envelope along so-called characteristics, which are circles in general.
Hellmuth STACHEL
doaj   +2 more sources

Fields of tangent sets and hofmann cones

Semigroup Forum, 1986
The Bony-Brezis theorem states that a closed subset F of a differentiable manifold M is invariant under the flow associated with a locally Lipschitzian vector field A if and only if for every \(p\in F\) the tangent vector A(p) belongs to the subtangent space of F at p.
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On tangent cones in Wasserstein space [PDF]

Proceedings of the American Mathematical Society, 2016
If M M is a smooth compact Riemannian manifold, let
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Tangent cones of concatenated numerical semigroups

Communications in Algebra
We study the tangent cone at the origin and the Hilbert series for a family of numerical semigroups generated by concatenation of arithmetic sequences. We prove that all the concatenation classes have Cohen-Macaulay tangent cones except the symmetric class, however, the symmetric class does satisfy Rossi's conjecture.
Mehta, Ranjana, Saha, Joydip, Sengupta, Indranath   +2 more
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Tangent star cones

Let \(X\) be an algebraic variety over a field \(k\). For \(x\in X\) a point on the variety, various notions of the cone to \(X\) at \(x\) have been considered, three of which have shown importance. The first two are defined, respectively, in terms of the linear forms (Zariski tangent space) and the initial forms (normal cone) of the equations ...
Simis, A., Ulrich, B., Vasconcelos, W.V.
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On the tangent cones to plurisubharmonic currents

, 2011
18 ...
Ghiloufi, Noureddine, Dabbek, Khalifa
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Algebraic aspects of tangent cones

Matemática Contemporânea, 1995
The present notes form an enlarged update of a series of lectures at the XII Escola de Álgebra, for a mixed audience of specialists whose expertise lied somewhere between commutative algebra and algebraic geometry. The notes do no claim complete originality.
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