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I am currently confronted with the following equation $$ 0=w''(t)(t^2-t)+w'(t)((2n-1)t^2-n)+w(t)(n-1)^2t $$ for $t\in(-1,1)$. So $w:(-1,1)\rightarrow\mathbb{R}$. The following assumption is also in force, $w(t)\in C^{2}(-1,1)$

I would like to prove that the solution to the above problem is unique (w=0). I have found some papers which prove uniqueness of such a class of equations with coefficients that contain singularities but none that are applicable in my case. Does anyone have an idea?

Edit: I apologise for not having added the following. n is an integer greater than or equal to 2.

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  • $\begingroup$ What is $n$ here? If e.g. $n=1$, then any constant is a solution. $\endgroup$ Commented Feb 1, 2023 at 21:22

2 Answers 2

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It is not unique. Maple solves your differential equation in terms of HeunC functions:

$$w \! \left(t \right) = c_{1} \mathit{HeunC} \left(2 n -1, n -1, n -2, -n^{2}+\frac{1}{2}, \frac{n^{2}}{2}+\frac{1}{2}, t\right)+c_{2} t^{-n +1} \mathit{HeunC} \left(2 n -1, -n +1, n -2, -n^{2}+\frac{1}{2}, \frac{n^{2}}{2}+\frac{1}{2}, t\right)$$ The first basic solution $$ \mathit{HeunC} \left(2 n -1, n -1, n -2, -n^{2}+\frac{1}{2}, \frac{n^{2}}{2}+\frac{1}{2}, t\right)$$ is analytic in the open unit disk.

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  • $\begingroup$ Oh thank you. Since the HeunC function is complex, to then find the first basic solution w(t) it suffices to take the real part? $\endgroup$
    – mhmmm1997
    Commented Feb 1, 2023 at 22:22
  • $\begingroup$ No need to take real part. If $n$ is real and $t \in (-1,1)$, $\mathit{HeunC} \left(2 n -1, n -1, n -2, -n^{2}+\frac{1}{2}, \frac{n^{2}}{2}+\frac{1}{2}, t\right)$ is real. $\endgroup$ Commented Feb 1, 2023 at 22:28
  • $\begingroup$ Do you have resources to consult in order to learn more about these functions? I am unable to find much describing even its most basic properties :/ $\endgroup$
    – mhmmm1997
    Commented Feb 2, 2023 at 0:49
  • $\begingroup$ See this and references given there. $\endgroup$ Commented Feb 2, 2023 at 19:30
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The set of $C^2$ solutions is one-dimensional, that is "unique up to a constant factor". The exponents at $0$ are $0$ and $1-n$, which gives a basis $w_1,w_2$ of solutions where $w_1$ is holomorphic, and $w_2$ blows up since $n\geq 2$.

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