Conjugated point is a point such that Jacobi´s equation has a non-trivial solution in that point. At least that is what I was tought.
The question than stands, if there exists such a point and hessian is indefinite, is there some lemma with which I can decide if such a point is a min. or max. of a certain functional?
PS: By Jacobi´s equation, I mean this:
$(f_{yy} - (f_{yz})')h - (f_{zz}h')' = 0$
$f_y$ stands for $\frac{\partial f}{\partial y}, f_z = \frac{\partial f}{\partial y'}$