منابع مشابه
Empty Real Enriques Surfaces and Enriques-einstein-hitchin 4-manifolds
N. Hitchin [H] proved that the Euler characteristic χ(E) and signature σ(E) of a compact orientable 4-dimensional Einstein manifold E satisfy the inequality |σ(E)| 6 2 3χ(E), the equality holding only if either E is flat or the universal covering X of E is a K3-surface and π1(E) = 1, Z/2, or Z/2× Z/2. In the latter cases, E is a K3-surface if π1 = 1, an Enriques surface if π1 = Z/2, or the quot...
متن کاملQuantum Periods for Certain Four-dimensional Fano Manifolds
We collect a list of known four-dimensional Fano manifolds and compute their quantum periods. This list includes all four-dimensional Fano manifolds of index greater than one, all fourdimensional toric Fano manifolds, all four-dimensional products of lower-dimensional Fano manifolds, and certain complete intersections in projective bundles.
متن کاملEnriques on Algebraic Geometry
tures of Bernoulli polynomials and gamma functions he has listed only the most important works. The bibliography is a very useful one. It is hardly to be expected that it should be complete. In fact I have found a considerable number of omissions by checking it against the partial bibliography which I have collected in an incidental way during the past fifteen years. It is natural to expect tha...
متن کاملAround real Enriques surfaces
We present a brief overview of the classiication of real Enriques surfaces completed recently and make an attempt to systemize the known clas-siication results for other special types of surfaces. Emphasis is also given to the particular tools used and to the general phenomena discovered; in particular , we prove two new congruence type prohibitions on the Euler characteristic of the real part ...
متن کاملCounting Enriques Quotients of a K3 Surface
Here TX and ρ(X) are respectively the transcendental lattice and the Picard number of X. U and E8 denote the unique even unimodular lattices of signature (1, 1) and (0, 8) respectively. l(L) of a nondegenerate lattice L is the number of minimal generators of the discriminant group AL = L ∗/L of L. Details on AL are found in [6]. As Keum remarks, the assumption (∗) is needed only for the implica...
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: Pure and Applied Mathematics Quarterly
سال: 2011
ISSN: 1558-8599,1558-8602
DOI: 10.4310/pamq.2011.v7.n4.a25