MHB Pointwise convergence of holomorphic functions

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A theorem in complex analysis states that a sequence of holomorphic functions converging pointwise to a function results in that function being holomorphic on a dense, open subset of the domain. The challenge presented is to find an example where the limit function is not holomorphic throughout the entire domain. A suggested approach to this problem involves using Runge's theorem, which can help identify a sequence of polynomials whose pointwise limit exhibits a point of discontinuity. This highlights the nuanced behavior of convergence in complex analysis. The discussion emphasizes the importance of understanding the conditions under which holomorphic functions maintain their properties in limits.
Radiator1
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Hello.

In my complex analysis book I've read a theorem which says that if a sequence $$\{ f_n \}$$ of holomorphic functions on a domain $$\Omega$$ converges pointwise to a function $$f$$, then $$f $$ is holomorphic on a dense, open subset of $$\Omega$$.

I know how to prove this theorem. I just find it hard to come up with an example of a sequence (as described above) for which the limit $f$ is not holomorphic on the entire $$\Omega$$.
 
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Radiator said:
Hello.

In my complex analysis book I've read a theorem which says that if a sequence $$\{ f_n \}$$ of holomorphic functions on a domain $$\Omega$$ converges pointwise to a function $$f$$, then $$f $$ is holomorphic on a dense, open subset of $$\Omega$$.

I know how to prove this theorem. I just find it hard to come up with an example of a sequence (as described above) for which the limit $f$ is not holomorphic on the entire $$\Omega$$.

Hi Radiator,

By application of Runge's theorem, you should be able to find a sequence of polynomials whose pointwise limit has a point of discontinuity.
 
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