Hyperplane section

Hyperplane section

In mathematics, a hyperplane section of a subset "X" of projective space "P""n" is the intersection of "X" with some hyperplane "H" — in other words we look at the subset "X""H" of those elements "x" of "X" that satisfy the single linear condition "L" = 0 defining "H" as a linear subspace. Here "L" or "H" can range over the dual projective space of non-zero linear forms in the homogeneous coordinates, up to scalar multiplication.

From a geometrical point of view, the most interesting case is when "X" is an algebraic subvariety — for more general cases, in mathematical analysis, some analogue of the Radon transform applies. In algebraic geometry, assuming therefore that "X" is "V", a subvariety not lying completely in any "H", the hyperplane sections are algebraic sets with irreducible components all of dimension "n" − 1. What more can be said is addressed by a collection of results known collectively as Bertini's theorem. The topology of hyperplane sections is studied in the topic of the Lefschetz hyperplane theorem and its refinements. Because the dimension drops by one in taking hyperplane sections, the process is potentially an inductive method for understanding varieties of higher dimension. A basic tool for that is the Lefschetz pencil.


Wikimedia Foundation. 2010.

Игры ⚽ Поможем написать курсовую

Look at other dictionaries:

  • Lefschetz hyperplane theorem — In mathematics, the Lefschetz hyperplane theorem states that a hyperplane section W of a non singular complex algebraic variety V , in complex projective space, inherits most of its algebraic topology from V . This allows certain geometrical… …   Wikipedia

  • Lefschetz pencil — In mathematics, a Lefschetz pencil is a construction in algebraic geometry considered by Solomon Lefschetz, in order to analyse the algebraic topology of an algebraic variety V . A pencil here is a particular kind of linear system of divisors on… …   Wikipedia

  • Weil cohomology theory — In algebraic geometry, a subfield of mathematics, a Weil cohomology or Weil cohomology theory is a cohomology satisfying certain axioms concerning the interplay of algebraic cycles and cohomology groups. The name is in honour of André Weil. Weil… …   Wikipedia

  • List of mathematics articles (H) — NOTOC H H cobordism H derivative H index H infinity methods in control theory H relation H space H theorem H tree Haag s theorem Haagerup property Haaland equation Haar measure Haar wavelet Haboush s theorem Hackenbush Hadamard code Hadamard… …   Wikipedia

  • Local cohomology — In mathematics, local cohomology is a chapter of homological algebra and sheaf theory introduced into algebraic geometry by Alexander Grothendieck. He developed it in seminars in 1961 at Harvard University, and 1961 2 at IHES. It was later… …   Wikipedia

  • Standard conjectures on algebraic cycles — In mathematics, the standard conjectures about algebraic cycles is a package of several conjectures describing the relationship of algebraic cycles and Weil cohomology theories. The original application envisaged by Grothendieck was to prove that …   Wikipedia

  • Hodge index theorem — In mathematics, the Hodge index theorem for an algebraic surface V determines the signature of the intersection pairing on the algebraic curves C on V . It says, roughly speaking, that the space spanned by such curves (up to linear equivalence)… …   Wikipedia

  • Max Noether's theorem — In mathematics, Max Noether s theorem in algebraic geometry may refer to at least six results of Max Noether. Noether s theorem usually refers to a result derived from work of his daughter Emmy Noether. There are several closely related results… …   Wikipedia

  • Séminaire Nicolas Bourbaki (1950–1959) — Continuation of the Séminaire Nicolas Bourbaki programme, for the 1950s. 1950/51 series *33 Armand Borel, Sous groupes compacts maximaux des groupes de Lie, d après Cartan, Iwasawa et Mostow (maximal compact subgroups) *34 Henri Cartan, Espaces… …   Wikipedia

  • Zariski surface — In algebraic geometry, a branch of mathematics, a Zariski surface is a surface over a field of characteristic p gt; 0 such that there is a dominant inseparable map of degree p from the projective plane to the surface. In particular, all Zariski… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”