Solution

ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2008/iii/paper-9/1/h/solution

False. On the additive topological group , put and . Both are invariant under left and right translations and induce the usual topology. The triangle inequality for follows from for . But
can be arbitrarily close to zero and arbitrarily large. Consequently no can satisfy both proposed inequalities. Compatibility of the two invariant metrics is topological equivalence, which need not be bilipschitz equivalence.

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