In this paper we give an explicit bound of ∆ g(t) u(t) and the local curvature estimates for the Ricci-harmonic flowunder the condition that the Ricci curvature is bounded along the flow. In the second part these local curvature estimates are extended to a class of generalized Ricci flow, introduced by the author [42], whose stable points give Ricci-flat metrics on a complete manifold, and which is very close to the (K, N)-super Ricci flow recently defined by Xiangdong Li and Songzi Li [35]. Next we propose a conjecture for Einstein's scalar field equations motivated by a result in the first part and the bounded L 2 -curvature conjecture recently solved by Klainerman, Rodnianski and Szeftel [26]. In the last two parts of this paper, we discuss two notions of "Riemann curvature tensor" in the sense of 24,67,68], respectively, and Li [44], whose "Ricci curvature" both give the standard Bakey-Émery Ricci curvature [1], and the forward and backward uniqueness for the Ricci-harmonic flow.
CONTENTS1. Introduction 2. Gradient and local curvature estimates 2.1. The boundedness of ∆ g(t) u(t) 2.2. Local curvature estimates 3. Results for a generalized Ricci flow 3.1. Long time existence 3.2. Bounded scalar curvature 4. Bounded L 2 -curvature conjecture for the Einstein scalar field equations 4.1. Initial value problem 4.2. Bounded L 2 -curvature conjecture for Einstein's equations 4.3. Bounded L 2 -curvature conjecture for the Einstein scalar field equations 5. Sm and Wylie-Yeroshkin Riemann curvature 5.1. Integral inequalities for scalar and Ricci curvatures 5.2. Killing vector fields with constant length 5.3. Remark on Rm L and Rm WY 6. Uniqueness for the Ricci-harmonic flow 6.1. Forward uniqueness 6.2. Backward uniqueness Appendix A. Evolution equations of the Ricci-harmonic flow 2010 Mathematics Subject Classification. Primary 53C44.