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Add property: ℵ₁-filtered colimits (WIP)#179

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aleph1-filtered-colimits
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Add property: ℵ₁-filtered colimits (WIP)#179
ScriptRaccoon wants to merge 3 commits into
mainfrom
aleph1-filtered-colimits

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@ScriptRaccoon ScriptRaccoon commented May 14, 2026

TBA

This PR adds two properties:

  • ℵ₁-filtered colimits
  • ℵ₁-filtered

As for ℵ₁-filtered, all categories have been decided. As for ℵ₁-filtered colimits, the following need to be decided, most of which look doable (except for FreeAb ...). At this point, I should also try to decide ℵ₁-accessible, which is open for several categories. Probably there is a general lemma which is similar to the Theorem 2.2.2 in Makkai-Paré. I think the following is true: a cauchy complete countable locally finite category is ℵ₁-accessible.


category of finite sets and injections
category of free abelian groups
category of metric spaces with continuous maps
category of schemes
delooping of the additive monoid of natural numbers
delooping of the additive monoid of ordinal numbers

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@ykawase5048 Can you perhaps help here?

@ScriptRaccoon ScriptRaccoon force-pushed the aleph1-filtered-colimits branch 2 times, most recently from a60230d to db9ec99 Compare May 14, 2026 23:29
@ScriptRaccoon ScriptRaccoon force-pushed the aleph1-filtered-colimits branch from db9ec99 to 10b8b74 Compare May 15, 2026 11:23
@ScriptRaccoon ScriptRaccoon force-pushed the aleph1-filtered-colimits branch from b60f325 to 89e1bdb Compare May 15, 2026 15:52
@ScriptRaccoon ScriptRaccoon changed the title Add property: ℵ₁-filtered colimits Add property: ℵ₁-filtered colimits (WIP) May 15, 2026
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