Cone cubic configurations of a ruled surface
نویسندگان
چکیده
منابع مشابه
Higher Order Contact on Cayley’s Ruled Cubic Surface
It is well known that Cayley’s ruled cubic surface carries a three-parameter family of twisted cubics sharing a common point, with the same tangent and the same osculating plane. We report on various results and open problems with respect to contact of higher order and dual contact of higher order for these curves.
متن کاملEffective Divisor Classes on a Ruled Surface
The Neron-Severi group of divisor classes modulo algebraic equivalence on a smooth algebraic surface is often not difficult to calculate, and has classically been studied as one of the fundamental invariants of the surface. A more difficult problem is the determination of those divisor classes which can be represented by effective divisors; these divisor classes form a monoid contained in the N...
متن کاملGenerators of Subcones of the Nef Cone of a Cubic Surface
● L = φ∗O(1) ● Li = L −Ei, the strict transform of a line through Pi = φ(Ei) ● Lij = 2L − (∑En) + Ei + Ej, the strict transform of a conic through the four points Pn with n ≠ i, j ● Bi = 3L− (∑En)−Ei, the strict transform of a cubic curve through all six points Pn, with a node at Pi. Let h be the class of a hyperplane in the embedding X ⊂ P3. For any line ` on X, the hyperplanes containing ` gi...
متن کاملDifferential Operators on a Cubic Cone
Consider in the space C with the coordinates x{ , x2, x3 the surface X defined by the equation x\ + x\ + x\ = 0. We prove the following theorem: T H E O R E M 1. Let D{X) be the ring of regular differential operators on X, and Da the ring of germs at the point 0 of analytic operators on X. Then 1°. the rings D(X) and Da are not Noetherian; 2°. for any natural number k the rings D{X) and Da are ...
متن کاملCubic Ruled Surfaces with Constant Distribution Parameter in E4
A first order invariant of ruled surfaces of E3 is the socalled distribution parameter d in a generator. It is defined as the limit of the quotient of the distance and the angle of the generator and its neighbour. Ruled surfaces with constant parameter of distribution are of special interest and have been studied by many authors. H. Brauner could prove that the only nontrivial cubic ruled surfa...
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: Transactions of the American Mathematical Society
سال: 1925
ISSN: 0002-9947
DOI: 10.1090/s0002-9947-1925-1501319-1