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Grassmannians are algebraic varieties whose points corresponds to vector subspaces of a fixed dimension in a fixed vector space.
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Non-trivial extension and tangent bundle isotropic Grassmannian
Let $V$ be a $2n$-dimensional vector space endowed with a nondegenerate skew-symmetric form $q:V \to V^\vee$. We define the isotropic Grassmannian to be
$$
X:=G_q(k,V)=\left\{[W] \in \mathbb P \left( …
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162
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Dimension of the Grassmannian of lines of an hyperplane section
Let $X$ be an isotropic Grassmannian, $Pic(X)=\mathbb Z$ (for example $X$ is a projective space or a quadric hypersurface). Consider a global section $s \in \Gamma(X,L)$, where $L$ is the generator of …
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63
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Vector bundle associated to orthogonal flag
Let $V$ be a $(2n+1)$-dimensional complex vector space endowed with a non-degenerate symmetric bilinear form $q:V\times V\to \mathbb C$.
Fix the notation:
$$
OG(n-1,n,V):=\{W_{n-1}\subset W_n\subset W …
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153
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Quadrics into Grassmannian as zero locus of a section
Let $V$ be a $\mathbb C$-vector space of dimension $n+2$ with a symmetric bilinear non-degenerate map $q: V \times V \to \mathbb C$. We define
$$
G(k+1,V):=\{\mathbb PW \subset \mathbb PV : \dim W=k+1 …
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0
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114
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Projective bundles on quadrics
Let us fix the setup over $\mathbb C$. Let $V$ be a $n$-dimensional vector space endowed with a non-degenerate symmetric bilinear form $q: V \times V \to \mathbb C$.
We have that
$$
Q^{n-2}=OG(1,V)=\{ …
0
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0
answers
293
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Tautological bundle and its dual
Let $X=\mathbb G(2,V)$ be the Grassmannian of $2$-planes in $V=\mathbb C^n$. We denote by $\mathcal S$ the tautological bundle on $X$.
In a paper there is written that "since $\mathcal S$ is a rank 2 …
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131
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Globally generated sheaf arising from orthogonal Grassmannian
Then one can define the orthogonal Grassmannians as
$$
OG(k,V)=\{\mathbb P W \subset \mathbb PV: \dim W=k \text{ and }W \text{ is }q-\text{isotropic}\} \subset G(k,V)
$$
which is naturally contained in …
0
votes
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answers
158
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Projectivization of the normal bundle of $\mathbb P^4$ in the 10-spinor variety
Let $X=S_{10} \subset \mathbb P^{15}$ be the 10-dimensional spinor variety in its minimal embedding. Consider a $\mathbb P^4 \subset S_{10}$, hence we can define the normal bundle $N=N_{\mathbb P^4|S_ …
2
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2
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281
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Extensions for a short exact sequence on Grassmannians
$\DeclareMathOperator\Sym{Sym}\DeclareMathOperator\Ext{Ext}$Let us consider a $n$-dimensional complex vector space $V$ and denote by $G(k,n)$ the Grassmannian of $k$-planes in $V$. We use the conventi …
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128
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Generalize spinor bundles over orthogonal Grassmannians
Having defined the spinor bundles over the orthogonal Grassmannians, can we produce some short exact sequences like the ones in the theorem above? …
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779
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Tangent bundle for orthogonal and isotropic Grassmannians
Finally the question: are there similar expressions of the tangent bundles for the other orthogonal and isotropic Grassmannians? Also a reference would be enough. …
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137
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Reference request & more: compute vector bundles for homogeneous $G$-varieties
Moreover, the homogeneous $G$-variety $G/P \cap Q$ dominates the generalized Grassmannians $G/P$ and $G/Q$.
$\require{AMScd}$
\begin{CD}
G/P \cap Q @>{q}>> G/Q\\
@V{p}VV\\
G/P. …
5
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1
answer
328
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Unsplitting sequence of vector bundles
Let $V$ be a $n$-dimensional complex vector space. Using Grothendieck's notation, we define the Grassmannian $G(k,V)$ as the space of $k$-quotients of $V$ or, equivalently, as
$$
G(k,V)=\{ \mathbb P W …
1
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110
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Global sections of a vector bundle over $OG(2,7)$
Let us work over $\mathbb C$, using the Grothendieck projectivization $\mathbb P():=Proj(Sym())$.
Consider a $7$-dimensional vector space $V$ endowed with a symmetric non-degenerate bilinear form $q:V …