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On gradient solitons of the Ricci-Harmonic flow ; Philipowski, Robert ; Thalmaier, Anton in Acta Mathematica Sinica (2015), 31(11), 1798-1804 In this paper we study gradient solitons to the Ricci flow coupled with harmonic map heat flow. We derive new identities on solitons similar to those on gradient solitons of the Ricci flow. When the ... [more ▼] In this paper we study gradient solitons to the Ricci flow coupled with harmonic map heat flow. We derive new identities on solitons similar to those on gradient solitons of the Ricci flow. When the soliton is compact, we get a classification result. We also discuss the relation with quasi-Einstein manifolds. [less ▲] Detailed reference viewed: 456 (47 UL)Martingales on manifolds with time-dependent connection Guo, Hongxin ; Philipowski, Robert ; Thalmaier, Anton in Journal of Theoretical Probability (2015), 28(3), 1038-1062 We define martingales on manifolds with time-dependent connection, extending in this way the theory of stochastic processes on manifolds with time-changing geometry initiated by Arnaudon, Coulibaly and ... [more ▼] We define martingales on manifolds with time-dependent connection, extending in this way the theory of stochastic processes on manifolds with time-changing geometry initiated by Arnaudon, Coulibaly and Thalmaier (2008). We show that some, but not all properties of martingales on manifolds with a fixed connection extend to this more general setting. [less ▲] Detailed reference viewed: 381 (47 UL)An entropy formula for the heat equation on manifolds with time-dependent metric, application to ancient solutions Guo, Hongxin ; Philipowski, Robert ; Thalmaier, Anton in Potential Analysis (2015), 42(2), 483-497 We introduce a new entropy functional for nonnegative solutions of the heat equation on a manifold with time-dependent Riemannian metric. Under certain integral assumptions, we show that this entropy is ... [more ▼] We introduce a new entropy functional for nonnegative solutions of the heat equation on a manifold with time-dependent Riemannian metric. Under certain integral assumptions, we show that this entropy is non-decreasing, and moreover convex if the metric evolves under super Ricci flow (which includes Ricci flow and fixed metrics with nonnegative Ricci curvature). As applications, we classify nonnegative ancient solutions to the heat equation according to their entropies. In particular, we show that a nonnegative ancient solution whose entropy grows sublinearly on a manifold evolving under super Ricci flow must be constant. The assumption is sharp in the sense that there do exist nonconstant positive eternal solutions whose entropies grow exactly linearly in time. Some other results are also obtained. [less ▲] Detailed reference viewed: 483 (41 UL)Heat equation in vector bundles with time-dependent metric Philipowski, Robert ; Thalmaier, Anton in Journal of the Mathematical Society of Japan (2015), 67(4), 1759-1769 We derive a stochastic representation formula for solutions of heat-type equations on vector bundles with time-dependent Riemannian metric over manifolds whose Riemannian metric is time-dependent as well ... [more ▼] We derive a stochastic representation formula for solutions of heat-type equations on vector bundles with time-dependent Riemannian metric over manifolds whose Riemannian metric is time-dependent as well. As a corollary we obtain a vanishing theorem for bounded ancient solutions under a curvature condition. Our results apply in particular to the case of differential forms. [less ▲] Detailed reference viewed: 362 (36 UL)A stochastic approach to the harmonic map heat flow on manifolds with time-dependent Riemannian metric Guo, Hongxin ; Philipowski, Robert ; Thalmaier, Anton in Stochastic Processes and Their Applications (2014), 124(11), 3535-3552 We first prove stochastic representation formulae for space–time harmonic mappings defined on manifolds with evolving Riemannian metric. We then apply these formulae to derive Liouville type theorems ... [more ▼] We first prove stochastic representation formulae for space–time harmonic mappings defined on manifolds with evolving Riemannian metric. We then apply these formulae to derive Liouville type theorems under appropriate curvature conditions. Space–time harmonic mappings which are defined globally in time correspond to ancient solutions to the harmonic map heat flow. As corollaries, we establish triviality of such ancient solutions in a variety of different situations. [less ▲] Detailed reference viewed: 302 (30 UL)A note on Chow's entropy functional for the Gauss curvature flow Guo, Hongxin ; Philipowski, Robert ; Thalmaier, Anton in Comptes Rendus de l'Académie des Sciences. Série I. Mathématique (2013), 351(21-22), 833-835 Based on the entropy formula for the Gauss curvature flow introduced by Bennett Chow, we define an entropy functional which is monotone along the unnormalized flow and whose critical point is a shrinking ... [more ▼] Based on the entropy formula for the Gauss curvature flow introduced by Bennett Chow, we define an entropy functional which is monotone along the unnormalized flow and whose critical point is a shrinking self-similar solution. [less ▲] Detailed reference viewed: 308 (14 UL)Entropy and lowest eigenvalue on evolving manifolds Guo, Hongxin ; Philipowski, Robert ; Thalmaier, Anton in Pacific Journal of Mathematics (2013), 264(1), 61-81 Detailed reference viewed: 299 (22 UL)Stochastic particle approximations for the Ricci flow on surfaces and the Yamabe flow Philipowski, Robert in Potential Analysis (2011), 35 We present stochastic particle approximations for the normalized Ricci flow on surfaces and for the non-normalized Yamabe flow on manifolds of arbitrary dimension. Detailed reference viewed: 139 (15 UL)Coupling of Brownian motions and Perelman's L-functional ; Philipowski, Robert in Journal of Functional Analysis (2011), 260 We show that on a manifold whose Riemannian metric evolves under backwards Ricci flow two Brownian motions can be coupled in such a way that their normalized L-distance is a supermartingale. As a ... [more ▼] We show that on a manifold whose Riemannian metric evolves under backwards Ricci flow two Brownian motions can be coupled in such a way that their normalized L-distance is a supermartingale. As a corollary, we obtain the monotonicity of the transportation cost between two solutions of the heat equation in the case that the cost function is the composition of a concave non-decreasing function and the normalized L-distance. In particular, it provides a new proof of a recent result of Topping [P. Topping, L-optimal transportation for Ricci flow, J. Reine Angew. Math. 636 (2009) 93–122]. [less ▲] Detailed reference viewed: 79 (14 UL)Non-explosion of diffusion processes on manifolds with time-dependent metric ; Philipowski, Robert in Mathematische Zeitschrift (2011), 268 We study the problem of non-explosion of diffusion processes on a manifold with time-dependent Riemannian metric. In particular we obtain that Brownian motion cannot explode in finite time if the metric ... [more ▼] We study the problem of non-explosion of diffusion processes on a manifold with time-dependent Riemannian metric. In particular we obtain that Brownian motion cannot explode in finite time if the metric evolves under backwards Ricci flow. Our result makes it possible to remove the assumption of non-explosion in the pathwise contraction result established by Arnaudon et al. (arXiv:0904.2762, to appear in Sém. Prob.). As an important tool which is of independent interest we derive an Itô formula for the distance from a fixed reference point, generalising a result of Kendall (Ann. Prob. 15:1491–1500, 1987). [less ▲] Detailed reference viewed: 123 (13 UL) |
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