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Then the intersection numbers of H and L are given by H 5 =1P, H 4 L=2P, H 3 L 2 =4P, H 2 L 3 =4P, H 1 L 4 =2P, L 5 =1P. So we have (6 H −2 E ) 5 = (2 H +2 L ) 5 = 3264 P . Fulton & MacPherson gave a precise description of exactly what "general position" means (although their two propositions about this are not quite right, and are corrected ...
One says that “the affine plane does not have a good intersection theory”, and intersection theory on non-projective varieties is much more difficult. A line on a P 1 × P 1 (which can also be interpreted as the non-singular quadric Q in P 3) has self-intersection 0, since a line can be moved off itself. (It is a ruled surface.)
The study of moduli spaces of curves, maps and other geometric objects, sometimes via the theory of quantum cohomology. The study of quantum cohomology, Gromov–Witten invariants and mirror symmetry gave a significant progress in Clemens conjecture. Enumerative geometry is very closely tied to intersection theory. [1]
In mathematics, the Fulton–Hansen connectedness theorem is a result from intersection theory in algebraic geometry, for the case of subvarieties of projective space with codimension large enough to make the intersection have components of dimension at least 1.
Suppose that M g,n is the moduli stack of compact Riemann surfaces of genus g with n distinct marked points x 1,...,x n, and M g,n is its Deligne–Mumford compactification. There are n line bundles L i on M g,n, whose fiber at a point of the moduli stack is given by the cotangent space of a Riemann surface at the marked point x i.
Since André Weil's initial definition of intersection numbers, around 1949, there had been a question of how to provide a more flexible and computable theory, which Serre sought to address. In 1958, Serre realized that classical algebraic-geometric ideas of multiplicity could be generalized using the concepts of homological algebra .
For example, the expected dimension of intersection of and is , the intersection of and has expected dimension , and so on. The definition of a Schubert variety states that the first value of j {\displaystyle j} with dim ( V j ∩ w ) ≥ i {\displaystyle \dim(V_{j}\cap w)\geq i} is generically smaller than the expected value n − k + i ...
Download as PDF; Printable version; In other projects Wikidata item; ... Pages in category "Intersection theory" The following 13 pages are in this category, out of ...