Differential manifold - Revision history

Vipul: 16 revisions

2008-05-18T19:38:38Z

16 revisions

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Vipul at 19:16, 5 April 2008

2008-04-05T19:16:19Z

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	Such that for every <math>p \in M</math>, there exists an open set <math>U \ni p</math> and a homeomorphism <math>U \cong V</math> where <math>V</math> is an open subset of <math>\R^n</math>, such that the sheaf restricted to <math>U</math> corresponds, via the homeomorphism, to the usual sheaf of infinitely differentiable functions on <math>V</math>.		Such that for every <math>p \in M</math>, there exists an open set <math>U \ni p</math> and a homeomorphism <math>U \cong V</math> where <math>V</math> is an open subset of <math>\R^n</math>, such that the sheaf restricted to <math>U</math> corresponds, via the homeomorphism, to the usual sheaf of infinitely differentiable functions on <math>V</math>.

			==Examples and properties==

			===Occurrence of differential manifolds===

			Differential manifolds occur in many different situations. The simplest example of a differential manifold is an open subset of Euclidean space: here, the coordinate chart is simply its inclusion into Euclidean space.

			More generally, differential manifolds include structures that locally look like Euclidean space, though they may have global properties that prevent them from being embeddable as open subsets of Euclidean space. For instance, a sphere is a differential manifold that can be given an atlas with two coordinate charts: the two open subsets are the complements of the north and south pole respectively, and the homeomorphisms to Euclidean space are stereographic projections.

			===Viewpoints of the collection of differential manifolds===

			Differential manifolds are often viewed as a category, where the ''morphisms'' are [[smooth map]]s. For more information, refer [[Category of differential manifolds with smooth maps]].

			==Constructions==

			===Sheaf of infinitely differentiable functions===

			One way of viewing the definition of a differential manifold is that it provides criteria on what functions can be viewed as differentiable, and what functions cannot be viewed as differentiable. All this data is captured in the [[sheaf of infinitely differentiable functions]]. This sheaf associates, to every open subset, a subalgebra of the algebra of continuous functions on that subset, which are deemed to be infinitely differentiable.

			===Tangent bundle===

Vipul at 19:10, 5 April 2008

2008-04-05T19:10:30Z

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	==Definition==		==Definition==

			{{quotation\|''If this is the first time you're seeing the definition of a differential manifold, you may want to explore the definition more carefully in the survey article [[How we define manifolds and why]]''}}
	===Definition in terms of atlases===		===Definition in terms of atlases===

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	Such that for every <math>p \in M</math>, there exists an open set <math>U \ni p</math> and a homeomorphism <math>U \cong V</math> where <math>V</math> is an open subset of <math>\R^n</math>, such that the sheaf restricted to <math>U</math> corresponds, via the homeomorphism, to the usual sheaf of infinitely differentiable functions on <math>V</math>.		Such that for every <math>p \in M</math>, there exists an open set <math>U \ni p</math> and a homeomorphism <math>U \cong V</math> where <math>V</math> is an open subset of <math>\R^n</math>, such that the sheaf restricted to <math>U</math> corresponds, via the homeomorphism, to the usual sheaf of infinitely differentiable functions on <math>V</math>.

	~~==Relation with other structures==~~

	~~===Weaker structures===~~

	* [[Topological manifold]]

Vipul: /* Definition in terms of sheaves */

2008-04-05T19:07:29Z

Definition in terms of sheaves

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	* A subsheaf of the [[sheaf of continuous functions]] from <math>M</math> to <math>\R</math>, which plays the role of the [[sheaf of infinitely differentiable functions]]		* A subsheaf of the [[sheaf of continuous functions]] from <math>M</math> to <math>\R</math>, which plays the role of the [[sheaf of infinitely differentiable functions]]

	Such that every ~~point has a neighborhood with~~ a homeomorphism to an open ~~set in~~ <math>\R^n</math>, such that the sheaf ~~restriction~~ to ~~that open set~~, ~~corresponds~~ to the sheaf of infinitely differentiable functions on ~~that open set~~.		Such that for every <math>p \in M</math>, there exists an open set <math>U \ni p</math> and a homeomorphism <math>U \cong V</math> where <math>V</math> is an open subset of <math>\R^n</math>, such that the sheaf restricted to <math>U</math> corresponds, via the homeomorphism, to the usual sheaf of infinitely differentiable functions on <math>V</math>.

	==Relation with other structures==		==Relation with other structures==

Vipul at 19:04, 5 April 2008

2008-04-05T19:04:58Z

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	* A [[topological manifold]] <math>M</math> (in particular, <math>M</math> is Hausdorff and second-countable)		* A [[topological manifold]] <math>M</math> (in particular, <math>M</math> is Hausdorff and second-countable)
	* An atlas of coordinate charts <math>\varphi_i:U_i \to V_i, i \in I</math> from <math>M</math> to <math>\R^n</math> (in other words an open cover <math>U_i</math> of <math>M</math> with homeomorphisms from each member <math>U_i</math> of the open cover to open sets <math>V_i</math> in <math>\R^n</math>)		* An [[atlas]] of coordinate charts <math>\varphi_i:U_i \to V_i, i \in I</math> from <math>M</math> to <math>\R^n</math> (in other words an open cover <math>U_i</math> of <math>M</math> with homeomorphisms from each member <math>U_i</math> of the open cover to open sets <math>V_i</math> in <math>\R^n</math>)

	satisfying the compatibility condition: the transition function between any two coordinate charts of the atlas is a diffeomomorphism of open subsets of <math>\R^n</math>. In symbols:		satisfying the compatibility condition: the transition function between any two coordinate charts of the atlas is a diffeomomorphism of open subsets of <math>\R^n</math>. In symbols:

Vipul: /* Definition */

2008-04-05T18:36:20Z

Definition

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	* A [[topological manifold]] <math>M</math> (in particular, <math>M</math> is Hausdorff and second-countable)		* A [[topological manifold]] <math>M</math> (in particular, <math>M</math> is Hausdorff and second-countable)
	* An atlas of coordinate charts <math>\varphi_i:U_i \to V_i, i \in I</math> on <math>M</math> to <math>\R^n</math> (in other words an open cover <math>U_i</math> of <math>M</math> with homeomorphisms from each member <math>U_i</math> of the open cover to open sets <math>V_i</math> in <math>\R^n</math>)		* An atlas of coordinate charts <math>\varphi_i:U_i \to V_i, i \in I</math> from <math>M</math> to <math>\R^n</math> (in other words an open cover <math>U_i</math> of <math>M</math> with homeomorphisms from each member <math>U_i</math> of the open cover to open sets <math>V_i</math> in <math>\R^n</math>)

	satisfying the compatibility condition: the transition function between any two coordinate charts of the atlas is a diffeomomorphism of open subsets of <math>\R^n</math>. In symbols:		satisfying the compatibility condition: the transition function between any two coordinate charts of the atlas is a diffeomomorphism of open subsets of <math>\R^n</math>. In symbols:

Vipul: /* Definition */

2008-04-03T20:57:43Z

Definition

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	* A [[topological manifold]] <math>M</math> (in particular, <math>M</math> is Hausdorff and second-countable)		* A [[topological manifold]] <math>M</math> (in particular, <math>M</math> is Hausdorff and second-countable)
	* An atlas of coordinate charts on <math>M</math> to <math>\R^n</math> (in other words an open cover of <math>M</math> with homeomorphisms from each member of the open cover to open sets in <math>\R^n</math>		* An atlas of coordinate charts <math>\varphi_i:U_i \to V_i, i \in I</math> on <math>M</math> to <math>\R^n</math> (in other words an open cover <math>U_i</math> of <math>M</math> with homeomorphisms from each member <math>U_i</math> of the open cover to open sets <math>V_i</math> in <math>\R^n</math>)

	satisfying the compatibility condition: the transition function between any two coordinate charts of the atlas is a diffeomomorphism of open subsets of <math>\R^n</math>.		satisfying the compatibility condition: the transition function between any two coordinate charts of the atlas is a diffeomomorphism of open subsets of <math>\R^n</math>. In symbols:

			<math>\varphi_i \circ \varphi_j^{-1}</math>

			is a homeomorphism when restricted to the set:

			<math>(\varphi_j(U_i \cap U_j))</math>

	By diffeomorphism, we here mean a <math>C^{\infty}</math> map with a <math>C^{\infty}</math> inverse.		By diffeomorphism, we here mean a <math>C^{\infty}</math> map with a <math>C^{\infty}</math> inverse.

	~~upto~~ the following equivalence:		However, we need to quotient out this data by the following equivalence:

	Two atlases of coordinate charts on a topological space define the same differential manifold structure if given any coordinate chart in one and any coordinate chart in the other, the transition function between them is a diffeomorphism.		Two atlases of coordinate charts on a topological space define the same differential manifold structure if taking their union still gives an atlas of coordinate charts. In other words, given any coordinate chart in one atlas and any coordinate chart in the other atlas, the transition function between them is a diffeomorphism.

	===Definition in terms of sheaves===		===Definition in terms of sheaves===
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	* A subsheaf of the [[sheaf of continuous functions]] from <math>M</math> to <math>\R</math>, which plays the role of the [[sheaf of infinitely differentiable functions]]		* A subsheaf of the [[sheaf of continuous functions]] from <math>M</math> to <math>\R</math>, which plays the role of the [[sheaf of infinitely differentiable functions]]

	Such that every point has a ~~neighbourhood~~ with a homeomorphism to an open set in <math>\R^n</math>, such that the sheaf restriction to that open set, corresponds to the sheaf of infinitely differentiable functions on that open set.		Such that every point has a neighborhood with a homeomorphism to an open set in <math>\R^n</math>, such that the sheaf restriction to that open set, corresponds to the sheaf of infinitely differentiable functions on that open set.

	==Relation with other structures==		==Relation with other structures==

Vipul: /* Definition in terms of sheaves */

2007-12-26T21:22:53Z

Definition in terms of sheaves

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	* A [[topological manifold]] <math>M</math>		* A [[topological manifold]] <math>M</math>
	* A subsheaf of the [[sheaf of continuous functions]] from <math>M</math> to <math>\R</math>, which plays the role of the [[sheaf of ~~infintely~~ differentiable functions]]		* A subsheaf of the [[sheaf of continuous functions]] from <math>M</math> to <math>\R</math>, which plays the role of the [[sheaf of infinitely differentiable functions]]

	Such that every point has a neighbourhood with a homeomorphism to an open set in <math>\R^n</math>, such that the sheaf restriction to that open set, corresponds to the sheaf of infinitely differentiable functions on that open set.		Such that every point has a neighbourhood with a homeomorphism to an open set in <math>\R^n</math>, such that the sheaf restriction to that open set, corresponds to the sheaf of infinitely differentiable functions on that open set.

Vipul: /* Definition in terms of sheaves */

2007-12-26T20:56:09Z

Definition in terms of sheaves

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	* A subsheaf of the [[sheaf of continuous functions]] from <math>M</math> to <math>\R</math>, which plays the role of the [[sheaf of infintely differentiable functions]]		* A subsheaf of the [[sheaf of continuous functions]] from <math>M</math> to <math>\R</math>, which plays the role of the [[sheaf of infintely differentiable functions]]

	Such that every point has a neighbourhood with a homeomorphism to an open set in <math>\R^n</math>, such that the ~~ring associated~~ to that open set ~~inthe sheaf~~, corresponds to the sheaf of infinitely differentiable functions on that open set.		Such that every point has a neighbourhood with a homeomorphism to an open set in <math>\R^n</math>, such that the sheaf restriction to that open set, corresponds to the sheaf of infinitely differentiable functions on that open set.

	==Relation with other structures==		==Relation with other structures==

Vipul: /* Definition in terms of sheaves */

2007-12-26T20:52:45Z

Definition in terms of sheaves

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	A '''differential manifold''' or '''smooth manifold''' is the following data:		A '''differential manifold''' or '''smooth manifold''' is the following data:

	* A [[topological ~~space~~]] <math>M</math>		* A [[topological manifold]] <math>M</math>
	* A subsheaf of the [[sheaf of continuous functions]] from <math>M</math> to <math>\R</math>, which plays the role of the [[sheaf of differentiable functions]]		* A subsheaf of the [[sheaf of continuous functions]] from <math>M</math> to <math>\R</math>, which plays the role of the [[sheaf of infintely differentiable functions]]
	~~{{fillin}}~~
			Such that every point has a neighbourhood with a homeomorphism to an open set in <math>\R^n</math>, such that the ring associated to that open set inthe sheaf, corresponds to the sheaf of infinitely differentiable functions on that open set.

	==Relation with other structures==		==Relation with other structures==