Proof.After Proposition 3.9 it is enough to consider the case where is equivalent to , and so we omit it from the notation and discussion.
Let be a symmetric monoidal functor satisfying the -excision condition, and let be the restriction of to . For a manifold with boundary , we prove that the canonical morphism is an equivalence. By -excision applied to the collar-gluing , where is the interior of , we obtain a diagram in
in which the vertical morphisms are equivalences. It now suffices to show that the top horizontal morphism is an equivalence. The equivalences of and are given by Theorem 3.24; the last equivalence by follows by Theorem 3.24 and Proposition 2.16.
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