A geometric space without conjugate points

Abstract

From a spray space $S$ on a manifold $M$ we construct a new geometric space $P$ of larger dimension with the following properties: 1. Geodesics in $P$ are in one-to-one correspondence with parallel Jacobi fields of $M$. 2. $P$ is complete if and only if $S$ is complete. 3. If two geodesics in $P$ meet at one point, the geodesics coincide on their common domain, and $P$ has no conjugate points. 4. There exists a submersion $\pi\colon P \to M$ that maps geodesics in $P$ into geodesics on $M$. Space $P$ is constructed by first taking two complete lifts of spray $S$. This will give a spray $S^{cc}$ on the second iterated tangent bundle $TTM$. Then space $P$ is obtained by restricting tangent vectors of geodesics for $S^{cc}$ onto a suitable $(2\dim M+2)$-dimensional submanifold of $TTTM$. Due to the last restriction, space $P$ is not a spray space. However, the construction shows that conjugate points can be removed if we add dimensions and relax assumptions on the geometric structure.