Date: Jan 20, 2013 3:31 AM
Author: Kaba
Subject: Re: What is pi_0?

20.1.2013 1:37, W. Dale Hall wrote:
> Kaba wrote:
>> Hi,
>>
>> In this page
>>
>> http://en.wikipedia.org/wiki/Indefinite_orthogonal_group
>>
>> there is the notation pi_0 in the topology section. What does it refer
>> to? I don't see how the homotopy groups could cover n = 0...
>>

> Note that for two maps f,g : (S^0, *) --> (X,*) to b homotopic, there
> must be a path connecting the images f(+1) and g(+1) of the non-
> distinguished points in X. In short, the homotopy set of (X,*) is just
> the set of path-components of X. In general, pi_0(X,*) has a
> distinguished point consisting of the path-component of the point *.


Makes sense. Thanks.

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