MHB Convergence in topological space

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In the discussion on convergence in topological spaces, the main focus is on proving that a sequence \( x_n \) converges to \( x \) if and only if the distance \( d(x_n, x) \) approaches zero as \( n \) approaches infinity. Participants clarify whether \( d \) represents a metric, noting that the problem may not apply to non-metrizable spaces. The conversation emphasizes the importance of defining "limit" in the context of metric spaces. The standard definition of convergence in metric spaces is referenced as a potential framework for the proof. Overall, the discussion seeks to establish a clear understanding of convergence within the specified topological context.
Julio1
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Let $(X,\tau)$ an topological space. Show that $x_n\to_{n\to \infty} x$ if and only if $d(x_n,x)\to_{n\to \infty} 0.$

Hello, any idea for begin? Thanks.
 
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Hi Julio,

Is $d$ supposed to be a metric? If so, the problem statement makes little sense, since there non-metrizable topological spaces.
 
What definition of "limit" are you using? If, as your use of "d" implies, this is a metric space, that looks pretty much like the standard definition of "limit" in a metric space.
 
We all know the definition of n-dimensional topological manifold uses open sets and homeomorphisms onto the image as open set in ##\mathbb R^n##. It should be possible to reformulate the definition of n-dimensional topological manifold using closed sets on the manifold's topology and on ##\mathbb R^n## ? I'm positive for this. Perhaps the definition of smooth manifold would be problematic, though.

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