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identity map (Definition)

Definition If $X$ is a set, then the identity map in $X$ is the mapping that maps each element in $X$ to itself.

Properties

  1. An identity map is always a bijection.
  2. Suppose $X$ has two topologies $\tau_1$ and $\tau_2$ . Then the identity mapping $I:(X,\tau_1)\to (X,\tau_2)$ is continuous if and only if $\tau_1$ is finer than $\tau_2$ , i.e., $\tau_1\subset\tau_2$ .
  3. The identity map on the $n$ -sphere, is homotopic to the antipodal map $A:S^n\to S^n$ if $n$ is odd [1].

References

1
V. Guillemin, A. Pollack, Differential topology, Prentice-Hall Inc., 1974.




"identity map" is owned by bwebste. [ full author list (2) | owner history (1) ]
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See Also: zero map, identity matrix

Other names:  identity mapping, identity operator, identity function
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Cross-references: odd, antipodal map, finer, continuous, topologies, bijection, mapping
There are 123 references to this entry.

This is version 4 of identity map, born on 2003-11-01, modified 2006-10-15.
Object id is 5418, canonical name is IdentityMap.
Accessed 12748 times total.

Classification:
AMS MSC03E20 (Mathematical logic and foundations :: Set theory :: Other classical set theory )

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