3 citations · 12 across the 17 of their papers we have counts for
17 papers
Fundamental forms and infinitesimal symmetries of projective varieties
Jun-Muk Hwang, Qifeng Li
We give a bound on the dimension of the linear automorphism group of a projective variety in terms of its fundamental forms at a general point. Moreover, w…
Homological rigidity and Schur rigidity of Schubert varieties in rational homogeneous spaces
Cong Ding, Qifeng Li
A Schubert variety on a rational homogenous space is said to be homologically rigid, if any subvariety on representing the same homology class with must…
Minimal rational curves on equivariant compactifications of symmetric spaces
Jun-Muk Hwang, Qifeng Li
Let be a symmetric space of a complex linear algebraic group and let be a nonsingular equivariant compactification of . We investigate the question: when are min…
Characteristic conic connections and torsion-free principal connections
Jun-Muk Hwang, Qifeng Li
We study the relation between torsion tensors of principal connections on G-structures and characteristic conic connections on associated cone structures. We formulate sufficient c…
Lines on holomorphic contact manifolds and a generalization of -distributions to higher dimensions
Jun-Muk Hwang, Qifeng Li
Since the celebrated work by Cartan, distributions with \nobreak{small} growth vector have been studied extensively. In the holomorphic setting, there is a natural corres…
Recognizing the -horospherical manifold of Picard number 1 by varieties of minimal rational tangents
Jun-Muk Hwang, Qifeng Li
Pasquier and Perrin discovered that the -horospherical manifold of Picard number 1 can be realized as a smooth specialization of the rational homogeneous space…
Rigidity of projective symmetric manifolds of Picard number 1 associated to composition algebras
Yifei Chen, Baohua Fu, Qifeng Li
To each complex composition algebra , there associates a projective symmetric manifold of Picard number one, which is just a smooth hyperplane section o…
Minimal rational curves and 1-flat irreducible G-structures
Jun-Muk Hwang, Qifeng Li
1-flat irreducible G-structures, equivalently, irreducible G-structures admitting torsion-free affine connections, have been studied extensively in differential geometry, especiall…
Unbendable rational curves of Goursat type and Cartan type
Jun-Muk Hwang, Qifeng Li
We study unbendable rational curves, i.e., nonsingular rational curves in a complex manifold of dimension with normal bundles isomorphic to $\mathcal{O}_{\mathbb{P}^1}(1)^{\opl…
Rigidity of wonderful group compactifications under Fano deformations
Baohua Fu, Qifeng Li
For a complex connected semisimple linear algebraic group of adjoint type and of rank , De Concini and Procesi constructed its wonderful compactification , which is…
Characterizing symplectic Grassmannians by varieties of minimal rational tangents
Jun-Muk Hwang, Qifeng Li
We show that if the variety of minimal rational tangents (VMRT) of a uniruled projective manifold at a general point is projectively equivalent to that of a symplectic or an odd-sy…
Fano deformation rigidity of rational homogeneous spaces of submaximal Picard numbers
Qifeng Li
We study the question whether rational homogeneous spaces are rigid under Fano deformation. In other words, given any smooth connected family f:X -> Zof Fano manifolds, if one fibe…
Deformation of product of complex Fano manifolds
Qifeng Li
Let X be a connected family of complex Fano manifolds. We show that if some fiber is the product of two manifolds of lower dimensions, then so is every fiber. Combining with previo…
Smooth projective horospherical varieties with nef tangent bundles
Qifeng Li
We show that smooth projective horospherical varieties with nef tangent bundles are rational homogeneous spaces.
Quadro-quadric special birational transformations from projective spaces to smooth complete intersections
Qifeng Li
Let ϕ: \mathbb{P}^{r}\dashrightarrow Z be a birational transformation with a smooth connected base locus scheme, where Z\subseteq\mathbb{P}^{r+c} is a nondegenerate prime Fano mani…
Pseudo-effective and nef cones on spherical varieties
Qifeng LI
We show that nef cycle classes on smooth complete spherical varieties are effective, and the products of nef cycle classes are also nef. Let X be a smooth projective spherical vari…
Subvarieties of small codimension in smooth projective varieties
Qifeng Li
Let X\subsetneq\mathbb{P}_{\mathbb{C}}^{N} be an n-dimensional nondegenerate smooth projective variety containing an m-dimensional subvariety Y. Assume that either m>\frac{n}{2} an…