The equations of type II1 unprojection

نویسنده

  • Stavros Argyrios Papadakis
چکیده

The type II1 unprojection is, by definition, the generic complete intersection type II unprojection, in the sense of [P] Section 3.1, for the parameter value k = 1, and depends on a parameter n ≥ 2. Our main results are the explicit calculation of the linear relations of the type II1 unprojection for any value n ≥ 2 (Theorem 3.16) and the explicit calculation of the quadratic equation for the case n = 3 (Theorem 4.1). In addition, Section 5 contains applications to algebraic geometry.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Some calculations on type II1 unprojection

The type II1 unprojection is, by definition, the generic complete intersection type II unprojection, in the sense of [P] Section 3.1, for the parameter value k = 1, and depends on a parameter n ≥ 2. Our main results are the explicit calculation of the linear relations of the type II1 unprojection for any value n ≥ 2 (Theorem 3.16) and the explicit calculation of the quadratic equation for the c...

متن کامل

Remarks on Type III Unprojection

Type III unprojection plays a very important role in the birational geometry of Fano threefolds (cf. [CPR], [Ki], [BZ]). According to [Ki] p. 43, it was first introduced by A. Corti on his calculations of Fano threefolds of genus 6 and 7. It seems that at present a general definition of type III unprojection is still missing. After proving in Section 2 some general facts about residual ideals, ...

متن کامل

Type II Unprojection

Answering a question of M. Reid, we define and prove the Gorensteiness of the type II unprojection.

متن کامل

Parallel Kustin–miller Unprojection with an Application to Calabi–yau Geometry

Kustin–Miller unprojection constructs more complicated Gorenstein rings from simpler ones. Geometrically, it inverts certain projections, and appears in the constructions of explicit birational geometry. However, it is often desirable to perform not only one but a series of unprojections. The main aim of the present paper is to develop a theory, which we call parallel Kustin–Miller unprojection...

متن کامل

Type II1 Factors With A Single Generator

In the paper, we study the generator problem of type II1 factors. By defining a new concept closely related to the numbers of generators of a von Neumann algebra, we are able to show that a large class of type II1 factors are singly generated, i.e., generated by two self-adjoint elements. In particular, we show that most of type II1 factors, whose free entropy dimensions are known to be less th...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:

دوره   شماره 

صفحات  -

تاریخ انتشار 2007