Critical Point Classification: Inconclusive Hessian

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What is the general approach to take when the Hessian is inconclusive when classifying critical points? ie the determinant = 0?
 
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If det(H) = 0 and H has both positive and negative eigenvalues at x, then x is a saddle point for the function.

If not...then classifying degenerate critical points [det(H) = 0] becomes quite difficult from what I know. Thom's Splitting Lemma might work. It's sort of a parametrized version of the Morse lemma.
http://en.wikipedia.org/wiki/Splitting_lemma_(functions )

In general, I think it's safe to say that degenerate critical points are annoying haha.
 
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Prove $$\int\limits_0^{\sqrt2/4}\frac{1}{\sqrt{x-x^2}}\arcsin\sqrt{\frac{(x-1)\left(x-1+x\sqrt{9-16x}\right)}{1-2x}} \, \mathrm dx = \frac{\pi^2}{8}.$$ Let $$I = \int\limits_0^{\sqrt 2 / 4}\frac{1}{\sqrt{x-x^2}}\arcsin\sqrt{\frac{(x-1)\left(x-1+x\sqrt{9-16x}\right)}{1-2x}} \, \mathrm dx. \tag{1}$$ The representation integral of ##\arcsin## is $$\arcsin u = \int\limits_{0}^{1} \frac{\mathrm dt}{\sqrt{1-t^2}}, \qquad 0 \leqslant u \leqslant 1.$$ Plugging identity above into ##(1)## with ##u...
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