Algebraic Topology: Showing Cone(L(X,x)) is Homeomorphic to P(X,x)

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Discussion Overview

The discussion revolves around the question of whether the space Cone(L(X,x)) is homeomorphic to P(X,x), where L(X,x) represents loops based at x and P(X,x) represents paths based at x. Participants explore various approaches and mappings to establish this relationship, focusing on theoretical aspects of algebraic topology.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant proposes considering the product space (L(X,x) x I) and seeks a surjective map to P(X,x) but struggles to find a suitable quotient mapping.
  • Another participant questions the validity of the original claim by examining a simple case where X consists of a single point, leading to a contradiction regarding homeomorphism.
  • A different participant suggests modifying the approach by considering the quotient space (Cone(L(X,x)))/~ to address issues with mapping constant functions.
  • Another contribution discusses decomposing paths into loops and non-looping parts, proposing a mapping from F: (L(X,x)xN(X,x)xI) to P(X,x) and establishing conditions for bijection.
  • One participant notes the need for additional identifications in their construction, indicating the complexity of the proposed mappings.

Areas of Agreement / Disagreement

Participants express differing viewpoints on the validity of the original claim regarding homeomorphism, with some questioning its truth and others proposing alternative constructions. The discussion remains unresolved, with no consensus reached on the matter.

Contextual Notes

Participants acknowledge limitations in their approaches, including the need for specific identifications and the challenges of mapping constant functions. The discussion reflects a reliance on various assumptions and definitions that may impact the conclusions drawn.

nughret
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I am trying to show that the space Cone(L(X,x)) is homeomorphic to P(X,x)
where L(X,x) = {loops in X base point x} and
P(X,x) = {paths in X base point x}

I firstly considered (L(X,x) x I) and tried to find a surjective map to P(X,x) that would quotient out right but i couldn't seem to find it. For example i considered
(l,t) -> p where p is the path such that p(1)=l(t) and they agree naturally before
i.e. F((l,t))(s) = l(ts)

I was wondering if anyone could point me roughly the right way or just chip in with their own thoughts
 
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Why should this be true?

If I take the simplest case X={x} then L(X,x)=P(X,x)={the constant path at x}. Cone(L(X,x)) is just [0,1] which is not homeomorphic to a point.
 
Yes your example is clear and i to was running into similar problems when trying to consider where to map (c(x),t) for different values of t on a general space. The task was set by someone who is knowledgeable about the subject so maybe if instead of the cone we consider

(Cone(L(X,x)))/~ where (c(x),a) ~ (c(x),b), c(x) is the function with constat value x. This would then clear up the problem of how to map the constant function and we would have F(c(x),t) = F(l,0) = c(x).(l any loop)

Then the problem remains the same, but if we consider the above identification made, it would appear natural to consider a method similar to my first post however i cannot manage to tweak it correctly
 
Consider decomposing a path,p, into a loop,l, and a non looping part,n, and a time,t, at the point where we connect these paths: p = l (+t) n
where for two paths a,b such that a(1)=b(0) we have (for t not equal 1,0)
(a (+t) b) (s) = a(s/t) , 0<s<t
b((s-t)/(1-t)) , t<s<1
and (a (+0) b) (s) = a(0)
(a (+1) b) (s) = a(s)

Motivitated by this define the map from F: (L(X,x))x(N(X,x))xI -> P(X,x)
where N(X,x) is the set of non looping maps n belongs to N(X,x) => n(t) is not equal to n(0)=x for all t>0 (strictly)
Then F(l,t,n) = F(l',t',n') => l (+t) n = l' (+t') n' =>
(t and t' not equal to 0)
Then WlOG assume t is greater than or equal to t' then if t is strictly greater we would have that one path took the value x at this time whilst the other didn't a contradiction => t = t'
and it then follows l = l' , n = n'
Now let t = 0 , then F(l,0,n) = F(l',t',n') then it is clear t' =0 , we have no condition on l,n

Hence we can find a bijection from Cone(L(X,x)xN(X,x)) to P(X,x) as i don't wish to consider the different possible topologies let us assume this is a continuous map.
Then if the original statement (or its revised version) was true then we must have that
Cone(L(X,x)xN(X,x)) is homeomorphic to (Cone(L(X,x)))/~
Do the above constuctions appear correct?
 
Re reading i see that we must also make the identification (l,1,n) ~' (l,1,n')
But then we will just get ; Cone(L(X,x)xN(X,x))/~'
 

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