Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:…3 e (a)s ) assumed asymptotically flat (therefore noncompact) at spatial infinity and geodesically complete [so that, due to the Hopf-Rinow theorem [39], every two points of Σ τ may be connected by a minimizing geodesic segment and there exists a point p ∈ Σ τ from which Σ τ is geodesically…
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