Does Anyone Understand the Conway Base 13 Function?

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The Conway base 13 function is presented as a counterexample to the converse of the Intermediate Value Theorem, indicating that it is not continuous despite the theorem's expectations. The Wikipedia article lacks clarity in defining the function, leading to confusion about its properties, including whether it is a surjection onto (0,1). Users express a need for a clearer explanation and a more detailed understanding of the function's behavior. A linked paper offers additional insights but does not fully resolve the ambiguities. Overall, there is a call for more comprehensive resources to better understand the Conway base 13 function.
LukeD
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So I was browsing Wikipedia, and I stumbled across this article: http://en.wikipedia.org/wiki/Conway_base_13_function

The article claims that the Conway base 13 function, as a function from (0,1) to the reals is a counter example to the converse of the Intermediate Value Theorem (i.e., that for any a, b in (0,1) if f(a) < f(b), then for any c between f(a) and f(b), there is an x between a and b such that f(x) = c, but the function is not continuous)

The function sounds like it is very interesting; however, the article as written is very sparse and the definition of the function is not very clear to me. Maybe I'm misunderstanding the definition, but as it's written, it doesn't even seem to be a surjection to (0,1) though the article claims that it is.

Unfortunately, a google search of the function didn't bring anything up other than the wikipedia article. Is there anyone who understands this function who could give clear definition of it?
 
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Here is a more elaborated paper:
https://www.uccs.edu/Documents/goman/Converse%20of%20IVT.pdf
 
There are probably loads of proofs of this online, but I do not want to cheat. Here is my attempt: Convexity says that $$f(\lambda a + (1-\lambda)b) \leq \lambda f(a) + (1-\lambda) f(b)$$ $$f(b + \lambda(a-b)) \leq f(b) + \lambda (f(a) - f(b))$$ We know from the intermediate value theorem that there exists a ##c \in (b,a)## such that $$\frac{f(a) - f(b)}{a-b} = f'(c).$$ Hence $$f(b + \lambda(a-b)) \leq f(b) + \lambda (a - b) f'(c))$$ $$\frac{f(b + \lambda(a-b)) - f(b)}{\lambda(a-b)}...

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