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feat(Topology/Group): Continuous isomorphism #16991
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PR summary 1b1887923bImport changes for modified filesNo significant changes to the import graph Import changes for all files
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…e-ver' into continuous-isomorphism
…-Base-ver' into continuous-isomorphism
/-- `ContinuousAddEquivClass F A B` states that `F` is a type of two-sided continuous additive | ||
isomomorphisms.-/ | ||
class ContinuousAddEquivClass (F : Type*) (A B : outParam Type*) [Add A] [Add B] | ||
[h : EquivLike F A B] [TopologicalSpace A] [TopologicalSpace B] extends AddEquivClass F A B : |
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Please avoid hom classes that use both algebra and topology. A better way is to introduce HomeomorphClass
and assume [AddEquivClass F A B] [HomeomorphClass F A B]
whenever needed.
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I think HomeomorphClass
doesn't exist at all. There is kind of a reason below:
Also, the design is under the suggextion below:
Is it safe to introduce two instances like this?
Is there a reason of avoiding the use of both algebra and topology?
Also, what about ContinuousMonoidHomClass
, in this sense why this exists?
Sorry that I donesn't know much about how to design APIs, I just follow the suggestions copying the existing codes and create this PR.
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@Thmoas-Guan earlier in Mathlib, we would mix algebra / topology in hom classes. This was necessary because they all extended FunLike
(or EquivLike
). However, we have since pulled this out and pass it as an argument instead. As such, the hom classes are now Prop
-valued, and it now makes more sense to split them into their respective parts, hence the suggestion from Yury not to mix.
Also, Yury knows we don't have HomeomorphClass
, that's why he's asking you to introduce it (it should be a separate PR though, on which this one will then depend). Note also: ContinuousMonoidHomClass
is deprecated.
Does this course of action make sense? Do you know how to proceed?
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I introduced HomeomorphClass
in PR #18689, may I ask for your help to review it too? Thank you
remove the class instance mixing algebra and topology
This PR/issue depends on:
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also remove lemmas already picked up by class instance
Define the continuous isomorphisms of multiplicative and additive topological group.