Is the solution to Laplace's equation harmonic over a path in space

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The discussion centers on whether the extreme values of a function V(x,y,z) that satisfies Laplace's equation along a specified path are found at the endpoints of that path. The question arises from the understanding that if V obeys the equation ∇²V(𝑟(t))=0, it may imply certain properties about its behavior. Participants note that the problem can be simplified to a one-dimensional context, suggesting that V should adhere to specific ordinary differential equations. The consensus leans towards the idea that, under these conditions, extreme values are indeed likely to occur at the endpoints. This highlights the relationship between harmonic functions and their extremal properties in defined paths.
quasar987
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I was hesistant wheter to post this in the physics of math section but it's much of math problem I think.

Suppose I have a function V(x,y,z) which obeys Laplace's equation over some path in space. That is to say, for some path parametrized by \vec{r}(t) = x(t)\hat{x} + y(t)\hat{y} + z(t)\hat{z}, a\leq t \leq b, \nabla ^2 V(\vec{r}(t))=0.

Is it true that the extreme values of V along that path are located at the end? (I.e. at V(\vec{r}(a)) and V(\vec{r}(b)))?
 
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