منابع مشابه
A Vanishing Result for Toric Varieties Associated with Root Systems
Consider a root system R and the corresponding toric variety VR whose fan is the Weyl fan and whose lattice of characters is given by the root lattice for R. We prove the vanishing of the higher cohomology groups for certain line bundles on VR by proving a purely combinatorial result for root systems. These results are related to a converse to Mazur’s Inequality for (simply-connected) split red...
متن کاملchannel estimation for mimo-ofdm systems
تخمین دقیق مشخصات کانال در سیستم های مخابراتی یک امر مهم محسوب می گردد. این امر به ویژه در کانال های بیسیم با خاصیت فرکانس گزینی و زمان گزینی شدید، چالش بزرگی است. مقالات متعدد پر از روش های مبتکرانه ای برای طراحی و آنالیز الگوریتم های تخمین کانال است که بیشتر آنها از روش های خاصی استفاده می کنند که یا دارای عملکرد خوب با پیچیدگی محاسباتی بالا هستند و یا با عملکرد نه چندان خوب پیچیدگی پایینی...
Automorphisms, Root Systems, and Compactifications of Homogeneous Varieties
Let G be a complex semisimple group and let H ⊆ G be the group of fixed points of an involutive automorphism of G. Then X = G/H is called a symmetric variety. In [CP], De Concini and Procesi have constructed an equivariant compactification X which has a number of remarkable properties, some of them being: i) The boundary is the union of divisors D1, . . . , Dr. ii) There are exactly 2 orbits. T...
متن کاملSmoothness of Schubert Varieties via Patterns in Root Systems
The aim of this article is to present a smoothness criterion for Schubert varieties in generalized flag manifolds G/B in terms of patterns in root systems. We generalize Lakshmibai-Sandhya’s well-known result that says that a Schubert variety in SL(n)/B is smooth if and only if the corresponding permutation avoids the patterns 3412 and 4231. Our criterion is formulated uniformly in general Lie ...
متن کاملNormality and Quadraticity for Special Ample Line Bundles on Toric Varieties Arising from Root Systems
We prove that special ample line bundles on toric varieties arising from root systems are projectively normal. Here the maximal cones of the fans correspond to the Weyl chambers, and special means that the bundle is torus-equivariant such that the character of the line bundle that corresponds to a maximal Weyl chamber is dominant with respect to that chamber. Moreover, we prove that the associa...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Kyushu Journal of Mathematics
سال: 1994
ISSN: 1340-6116
DOI: 10.2206/kyushujm.48.123