Commit 2024-11-27 13:34 37c90e46
View on Github →feat: uniform time lemma for the existence of global integral curves (#9013) Lemma 9.15 in Lee's Introduction to Smooth Manifolds:
Let
vbe a smooth vector field on a smooth manifoldM. If there existsε > 0such that for each pointx : M, there exists an integral curve ofvthroughxdefined on an open intervalIoo (-ε) ε, then every point onMhas a global integral curve ofvpassing through it. We only requirevto be $C^1$. To achieve this, we define the extension of an integral curveγby another integral curveγ', if they agree at a point inside their overlapping open interval domains. This utilises the uniqueness theorem of integral curves. We need this lemma to show that vector fields on compact manifolds always have global integral curves.