= Conjugate-point criterion for the Riemannian index form
On continuous piecewise smooth perpendicular fields with zero endpoints, the <Riemannian index form> is nonnegative exactly when no point strictly inside the <geodesic> segment is conjugate to its initial point. It is positive on every nonzero field exactly when no <conjugate point> occurs up to and including the final endpoint. At a first conjugate endpoint its nullspace consists of the endpoint-vanishing <Jacobi fields>. These statements distinguish nonnegative quadratic forms from strictly positive ones and do not assume global minimization.
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