A new approach to pointwise heat kernel upper bounds on doubling metric measure spaces |
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Authors: | Salahaddine Boutayeb Thierry Coulhon Adam Sikora |
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Institution: | 1. Faculté polydisciplinaire de Safi, Université Cadi Ayyad, 46000 Safi, Morocco;2. Mathematical Sciences Institute, The Australian National University, Canberra, ACT 0200, Australia;3. Department of Mathematics, Macquarie University, NSW 2109, Australia |
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Abstract: | On doubling metric measure spaces endowed with a strongly local regular Dirichlet form, we show some characterisations of pointwise upper bounds of the heat kernel in terms of global scale-invariant inequalities that correspond respectively to the Nash inequality and to a Gagliardo–Nirenberg type inequality when the volume growth is polynomial. This yields a new proof and a generalisation of the well-known equivalence between classical heat kernel upper bounds and relative Faber–Krahn inequalities or localised Sobolev or Nash inequalities. We are able to treat more general pointwise estimates, where the heat kernel rate of decay is not necessarily governed by the volume growth. A crucial role is played by the finite propagation speed property for the associated wave equation, and our main result holds for an abstract semigroup of operators satisfying the Davies–Gaffney estimates. |
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Keywords: | Heat kernels Metric measure spaces Nash inequalities Gagliardo&ndash Nirenberg inequalities Davies&ndash Gaffney estimates Dirichlet forms |
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