arXiv subjects

Jaehyun Hong

Publications and source records attributed to Jaehyun Hong.

21 records · Page 2Linked to original sources

arXiv2005

On closures of cycle spaces of flag domains

Open orbits D of noncompact real forms G_0 acting on flag manifolds of their semisimple complexifications G are considered. The unique orbit C of a maximal compact subgroup K_0 of G_0 in D can be regarded as a point in the (full) cycle space of D. The group theoretical cycle space is defined to be the connected component containing C of the intersection of the G-orbit of C with the full cycle space of D. The main result of the present article is that the group theoretical cycle space is closed in the full cycle space. In particular, if they have the same dimension, then they are equal. This follows from an analysis of the closure of the Akhiezer-Gindikin domain in any G-equivariant compactification of the affine symmetric space G/K, where K is the complexification of K_0 in G.

math.AG↗

arXiv2005

Rigidity of smooth Schubert varieties in Hermitian symmetric spaces

Schubert varieties are irreducible subvarieties of homogeneous manifold, which are important to understand the geometry of homogeneous manifold G/P and the action of the semisimple Lie group G. Consider the space of effective cycles in G/P with homology class equal to an integral multiple of the homology class of a Schubert variety X_w of type w. We will show that for a smooth Schubert variety X_w in Hermitian symmetric space with trivial exceptions, this cycle space is simple: any irreducible subvariety X with homology class [X]=r[X_w] is again a Schubert variety of type w.

math.DG↗

arXiv2004

Rigidity of singular Schubert varieties in Gr(m,n)

Let a=(p_1^{q_1}, ..., p_r^{q_r}) be a partition and a'=({p_1'}^{q_1'}, >..., {p_r'}^{q_r'}) be its conjugate. We will prove that if q_i, q_i > 1 for all i, then any irreducible subvariety X of Gr(m,n) whose homology class is an integral multiple of the Schubert class [σ_a] of type a is a Schubert variety of type a.

math.DG↗