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Completions and DK-equivalences of ${Θ_n}$-spaces

Miika Tuominen

TL;DR

The paper develops Rezk-style completion for $\Theta_n$-spaces, providing a family of completions in each dimension and a total completion that localizes Segal $\Theta_n$-spaces with respect to all completeness conditions. It defines and analyzes DK-equivalences in this higher-categorical setting, linking them to levelwise weak equivalences after appropriate localizations. Using an inductive suspension framework, it proves that horizontal and higher-dimensional completions preserve the essential enriched structure while turning Segal objects into complete ones. The results yield a precise characterization: for $Se^n(S)$-fibrant objects, DK-equivalences coincide with $Cplt^n(S)$-local equivalences, and complete Segal $\Theta_n$-spaces model $(\infty,n)$-categories up to these localizations. The constructions also provide a practical, dimension-by-dimension approach to completing higher categorical structures via a sequence of functorial completions and a total completion $T$.

Abstract

We establish Rezk completion functors for $Θ_n$ spaces with respect to each and all of the completeness conditions. As a consequence, we obtain a characterization of Dwyer-Kan equivalences between Segal $Θ_n$ spaces.

Completions and DK-equivalences of ${Θ_n}$-spaces

TL;DR

The paper develops Rezk-style completion for -spaces, providing a family of completions in each dimension and a total completion that localizes Segal -spaces with respect to all completeness conditions. It defines and analyzes DK-equivalences in this higher-categorical setting, linking them to levelwise weak equivalences after appropriate localizations. Using an inductive suspension framework, it proves that horizontal and higher-dimensional completions preserve the essential enriched structure while turning Segal objects into complete ones. The results yield a precise characterization: for -fibrant objects, DK-equivalences coincide with -local equivalences, and complete Segal -spaces model -categories up to these localizations. The constructions also provide a practical, dimension-by-dimension approach to completing higher categorical structures via a sequence of functorial completions and a total completion .

Abstract

We establish Rezk completion functors for spaces with respect to each and all of the completeness conditions. As a consequence, we obtain a characterization of Dwyer-Kan equivalences between Segal spaces.

Paper Structure

This paper contains 7 sections, 68 theorems, 73 equations.

Key Result

Theorem 1.1

For each $1\leq k\leq n$ there is a functor localizing Segal $\Theta_n$-spaces with respect to the completeness condition in dimension $k$ via a DK-equivalence.

Theorems & Definitions (127)

  • Theorem 1.1
  • Theorem 1.2
  • Theorem 1.3
  • Definition 2.1
  • Definition 2.3
  • Proposition 2.5
  • Definition 2.6
  • Definition 2.7
  • Theorem 2.8
  • Definition 2.10
  • ...and 117 more