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Grassmannians are algebraic varieties whose points corresponds to vector subspaces of a fixed dimension in a fixed vector space.

1 vote
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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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1 vote
0 answers
162 views

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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1 vote
0 answers
63 views

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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1 vote
0 answers
153 views

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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1 vote
0 answers
114 views

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)=\{ …
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0 votes
0 answers
293 views

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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1 vote
0 answers
131 views

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 …
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0 votes
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158 views

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_ …
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2 votes
2 answers
281 views

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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1 vote
0 answers
128 views

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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2 votes
1 answer
779 views

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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4 votes
0 answers
137 views

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. …
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5 votes
1 answer
328 views

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 …
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1 vote
0 answers
110 views

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 …
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