Learn About Grassmann Manifolds: Intro, Charts, Atlas

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    Grassmann Manifolds
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Discussion Overview

The discussion centers around Grassmann manifolds, specifically seeking an introduction, details on charts and atlases, and related subjects. The scope includes theoretical aspects of differential topology and manifold theory.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant requests an introduction to Grassmann manifolds, including details on charts and atlases, as well as related subjects.
  • Another participant suggests reading "Differentiable Manifolds" by Milnor as a resource.
  • A follow-up inquiry asks for the specific title of the book recommended.
  • Additional comments mention that lecture notes on differential topology have been available for decades, and reference is made to the book "Characteristic Classes."
  • One participant provides an example of the set of all lines through the origin in three-dimensional space, explaining how these lines can be covered by coordinate charts and establishing that this set is a 2-dimensional manifold.
  • A later post questions the isomorphism between the set of lines through the origin and the set of planes through the origin, prompting further exploration of this relationship.

Areas of Agreement / Disagreement

The discussion does not appear to reach a consensus, as participants present various resources and examples without resolving the initial request for a comprehensive introduction to Grassmann manifolds.

Contextual Notes

Some assumptions about the definitions and properties of Grassmann manifolds may not be explicitly stated, and the discussion includes unresolved mathematical relationships between lines and planes in three-dimensional space.

bigli
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I need to following subjects about GRASSMANN MANIFOLDS,what do I?

1)introduction(together with details)

2)charts,atlas(together with details)

3)depended subjects
 
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read milnor, differentiable manifolds
 
the book name

what is your book name that introduce to me ??
 
these are leture notes on differential topology, widely available for several decades. or maybe now in the book characteristic classes.
 
heres an example: the set G of all lines through the origin of (x,y,z) space. since each such line is determined by any other point, consider the three planes x=1, y=1, z=1.

each line through the origin contains a point with at least one non zero coordinate, hence with some coordinate equal to 1, so each such line meets at least one of those planes in a unique point.

thus the set of all lines in G is covered by three sets each isomorphic to a plane. hence G is a 2 dimensional manifold with three coordinate charts. moreover, there is a 2:1 surjection from the unit sphere onto G, since each point of the sphere determines one line through (0,0,0), and each such line meets the sphere twice.
 
now consider planes through (0,0,0) in space. can you see why this set is isomorphic to the previous set of lines through (0,0,0)?
 

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