Zulip Chat Archive
Stream: mathlib4
Topic: Why are limits in category noncomputable?
Kenny Lau (Jun 25 2025 at 14:04):
Was this to prevent diamonds?
Kevin Buzzard (Jun 25 2025 at 14:09):
Because you can't compute them in general?
Kenny Lau (Jun 25 2025 at 14:09):
well i can just form the product type (in the category Type)
Aaron Liu (Jun 25 2025 at 14:11):
That a specific example of a limit which is computable
Aaron Liu (Jun 25 2025 at 14:11):
that doesn't mean they're computable in general
Joël Riou (Jun 25 2025 at 14:14):
For binary products with good definitional properties, we have the API FiniteChosenProducts.
Adam Topaz (Jun 25 2025 at 14:28):
And in general you can work with an explicit (co)limit (co)cone if you want to have some special properties of the (co)limit.
Antoine Chambert-Loir (Jun 25 2025 at 22:02):
That won't give you an algorithm to decide whether two distinct objects are some level stay distinct in every subsequent level.
Last updated: Dec 20 2025 at 21:32 UTC