ON CLASSIFICATION OF PROJECTIVE VARIETIES WITH NON-INTEGRAL NEF VALUES

2001 ◽  
Vol 22 (02) ◽  
pp. 255-262
Author(s):  
YICAI ZHAO
Keyword(s):  
Projective Varieties

scholarly journals On the classification of 3-dimensionalSL2(ℂ)-varieties

2000 ◽  
Vol 157 ◽  
pp. 129-147 ◽  
Author(s):  
Stefan Kebekus
Keyword(s):  
Automorphism Group ◽  
Semisimple Group ◽  
Picard Number ◽  
Projective Varieties ◽  
3 Dimensional

In the present work we describe 3-dimensional complexSL2-varieties where the genericSL2-orbit is a surface. We apply this result to classify the minimal 3-dimensional projective varieties with Picard-number 1 where a semisimple group acts such that the generic orbits are 2-dimensional.This is an ingredient of the classification [Keb99] of the 3-dimensional relatively minimal quasihomogeneous varieties where the automorphism group is not solvable.

scholarly journals On hyperquadrics containing projective varieties

2020 ◽  
Vol 32 (5) ◽  
pp. 1199-1209
Author(s):  
Euisung Park
Keyword(s):  
Projective Variety ◽  
Minimal Degree ◽  
Zero Set ◽  
Projective Varieties ◽  
Quadratic Equations ◽  
Linearly Independent ◽  
Del Pezzo ◽  
Classification Of Varieties ◽  
Irreducible Projective Variety

AbstractClassical Castelnuovo Lemma shows that the number of linearly independent quadratic equations of a nondegenerate irreducible projective variety of codimension c is at most {{{c+1}\choose{2}}} and the equality is attained if and only if the variety is of minimal degree. Also G. Fano’s generalization of Castelnuovo Lemma implies that the next case occurs if and only if the variety is a del Pezzo variety. Recently, these results are extended to the next case in [E. Park, On hypersurfaces containing projective varieties, Forum Math. 27 2015, 2, 843–875]. This paper is intended to complete the classification of varieties satisfying at least {{{c+1}\choose{2}}-3} linearly independent quadratic equations. Also we investigate the zero set of those quadratic equations and apply our results to projective varieties of degree {\geq 2c+1}.

On the adjunction theoretic classification of projective varieties

1991 ◽  
Vol 290 (1) ◽  
pp. 31-62 ◽  
Author(s):  
Mauro C. Beltrametti ◽  
M. Lucia Fania ◽  
Andrew J. Sommese
Keyword(s):  
Projective Varieties ◽  
Theoretic Classification

scholarly journals Some results on equivariant contact geometry for partial flag varieties

2016 ◽  
Vol 27 (08) ◽  
pp. 1650066 ◽  
Author(s):  
Peter Crooks ◽  
Steven Rayan
Keyword(s):  
Vector Bundles ◽  
Contact Structures ◽  
Flag Varieties ◽  
Contact Manifolds ◽  
Projective Varieties ◽  
Simply Connected ◽  
Complex Projective ◽  
Special Case ◽  
Partial Flag Varieties

We study equivariant contact structures on complex projective varieties arising as partial flag varieties [Formula: see text], where [Formula: see text] is a connected, simply-connected complex simple group of type ADE and [Formula: see text] is a parabolic subgroup. We prove a special case of the LeBrun-Salamon conjecture for partial flag varieties of these types. The result can be deduced from Boothby’s classification of compact simply-connected complex contact manifolds with transitive action by contact automorphisms, but our proof is completely independent and relies on properties of [Formula: see text]-equivariant vector bundles on [Formula: see text]. A byproduct of our argument is a canonical, global description of the unique [Formula: see text]-invariant contact structure on the isotropic Grassmannian of 2-planes in [Formula: see text].

scholarly journals Regularity of structure sheaves of varieties with isolated singularities

2020 ◽  
pp. 2050039
Author(s):  
Joaquín Moraga ◽  
Jinhyung Park ◽  
Lei Song
Keyword(s):  
Recent Result ◽  
Projective Variety ◽  
Isolated Singularities ◽  
Projective Varieties ◽  
Multiplier Ideals

Let [Formula: see text] be a non-degenerate normal projective variety of codimension [Formula: see text] and degree [Formula: see text] with isolated [Formula: see text]-Gorenstein singularities. We prove that the Castelnuovo–Mumford regularity [Formula: see text], as predicted by the Eisenbud–Goto regularity conjecture. Such a bound fails for general projective varieties by a recent result of McCullough–Peeva. The main techniques are Noma’s classification of non-degenerate projective varieties and Nadel vanishing for multiplier ideals. We also classify the extremal and the next to extremal cases.

On Projective Varieties with Projectively Equivalent Zero-Dimensional Linear Sections

1992 ◽  
Vol 35 (1) ◽  
pp. 3-13 ◽  
Author(s):  
E. Ballico
Keyword(s):  
Positive Characteristic ◽  
Projective Varieties ◽  
Partial Classification ◽  
Linear Sections ◽  
Classification Of Varieties

AbstractHere we give a partial classification of varieties X ⊂ Pn such that any two general zero-dimensional linear sections are projectively equivalent. They exist (with deg(X) > codim(X) + 2) only in positive characteristic.

Note on the spectral classification of carbon stars in the photographic infrared region

1966 ◽  
Vol 24 ◽  
pp. 21-23
Author(s):  
Y. Fujita
Keyword(s):  
Infrared Region ◽  
Spectral Classification ◽  
Carbon Stars

We have investigated the spectrograms (dispersion: 8Å/mm) in the photographic infrared region fromλ7500 toλ9000 of some carbon stars obtained by the coudé spectrograph of the 74-inch reflector attached to the Okayama Astrophysical Observatory. The names of the stars investigated are listed in Table 1.

Diagnostic Value of Electron Microscopy in Soft Tissue Tumors

1970 ◽  
Vol 28 ◽  
pp. 220-221
Author(s):  
Gerald Fine ◽  
Azorides R. Morales
Keyword(s):  
Cardiac Myxoma ◽  
Osteogenic Sarcoma ◽  
Diagnostic Value ◽  
Soft Tissue Tumors ◽  
Amelanotic Melanoma ◽  
Growth Patterns ◽  
Light Microscopic Level ◽  
Mesenchymal Tumors ◽  
Good Agreement

For years the separation of carcinoma and sarcoma and the subclassification of sarcomas has been based on the appearance of the tumor cells and their microscopic growth pattern and information derived from certain histochemical and special stains. Although this method of study has produced good agreement among pathologists in the separation of carcinoma from sarcoma, it has given less uniform results in the subclassification of sarcomas. There remain examples of neoplasms of different histogenesis, the classification of which is questionable because of similar cytologic and growth patterns at the light microscopic level; i.e. amelanotic melanoma versus carcinoma and occasionally sarcoma, sarcomas with an epithelial pattern of growth simulating carcinoma, histologically similar mesenchymal tumors of different histogenesis (histiocytoma versus rhabdomyosarcoma, lytic osteogenic sarcoma versus rhabdomyosarcoma), and myxomatous mesenchymal tumors of diverse histogenesis (myxoid rhabdo and liposarcomas, cardiac myxoma, myxoid neurofibroma, etc.)

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