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Why is the question closed, although no one can answer it? Using topological structure we can define continuous functions and convergent sequences. Why differentiable functions could not be defined in terms of the topology?
Joseph Van Name: you should define a metric on $X$ at first for you idea to be right or have a meaning. I am not sure. This like the answer of Todd Trimble, on metric space.
you can say that differential topology is dealing with differentiable functions on differentiable manifolds. My question is dealing with differentiable functions on topological space in general. Is there an analogy in general topological space without any added structure or restrictions?