| Abstract: |
| A global attractor is a notion for a topological semi-dynamical system whose phase space is a metric space. It should be noticed that the notion of a global attractor depends on the specific choice of a metric. In this talk, we ``define`` global attractors in the context of the ``non-existence of natural metrics`` of the phase space and study those properties. This includes a case where the phase space is a Fr\`{e}chet space, which is motivated by differential equations with unbounded delay. We obtain sufficient conditions for the existence, which will be applied to such equations. |
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