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homeotopy (Definition)

Let $X$ be a topological Hausdorff space. Let ${\rm Homeo}(X)$ be the group of homeomorphisms $X\to X$ , which can be also turn into a topological space by means of the compact-open topology. And let $\pi_k$ be the k-th homotopy group functor.

Then the k-th homeotopy is defined as: $${\cal{H}}_k(X)=\pi_k({\rm Homeo}(X))$$ that is, the group of homotopy classes of maps $S^k\to {\rm Homeo}(X)$ . Which is different from $\pi_k(X)$ , the group of homotopy classes of maps $S^k\to X$ .

One important result for any low dimensional topologist is that for a surface $F$ $${\cal{H}}_0(F)={\rm Out}(\pi_1(F))$$ which is the $F$ 's extended mapping class group.

Reference

G.S. McCarty, Homeotopy groups, Trans. A.M.S. 106(1963)293-304.




"homeotopy" is owned by juanman. [ full author list (2) ]
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See Also: isotopy, group, homeomorphism, group, isotopy, homeomorphism

Other names:  mapping class group
Keywords:  homotopy group functor
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Cross-references: surface, maps, classes, homotopy, functor, homotopy group, compact-open topology, topological space, homeomorphisms, group, Hausdorff space
There are 3 references to this entry.

This is version 14 of homeotopy, born on 2006-02-20, modified 2006-12-24.
Object id is 7642, canonical name is Homeotopy.
Accessed 2451 times total.

Classification:
AMS MSC20F38 (Group theory and generalizations :: Special aspects of infinite or finite groups :: Other groups related to topology or analysis)

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