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@malarbol malarbol commented Dec 1, 2025

This PR introduces the new modules:

  • action-of-isometries-on-cauchy-approximations-pseudometric-spaces.lagda.md;
  • action-of-short-maps-on-cauchy-approximations-metric-spaces.lagda.md;
  • action-of-short-maps-on-cauchy-approximations-pseudometric-spaces.lagda.md.

to refactor these concepts in their own modules.

malarbol and others added 25 commits November 22, 2025 18:28
…dometric-spaces.lagda.md

Co-authored-by: Fredrik Bakke <fredrbak@gmail.com>
…dometric-spaces.lagda.md

Co-authored-by: Fredrik Bakke <fredrbak@gmail.com>
…dometric-spaces.lagda.md

Co-authored-by: Fredrik Bakke <fredrbak@gmail.com>
…dometric-spaces.lagda.md

Co-authored-by: Fredrik Bakke <fredrbak@gmail.com>
…dometric-spaces.lagda.md

Co-authored-by: Fredrik Bakke <fredrbak@gmail.com>
--lossy-unification breaks some proof of UniMath#1726
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malarbol commented Dec 1, 2025

Because we didn't have Cauchy pseudocompletions at the time, the definitions of these actions were in the cauchy-approximations-XXX modules while the fact that they induce short maps / isometries were in the cauchy-pseudocompletions-XXX modules.

@malarbol malarbol changed the title Refactor function actions cauchy approximations Refactor function actions on cauchy approximations Dec 2, 2025
@malarbol malarbol mentioned this pull request Dec 2, 2025
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  • action-of-isometries-on-cauchy-approximations-pseudometric-spaces.lagda.md;
  • action-of-short-maps-on-cauchy-approximations-metric-spaces.lagda.md;
  • action-of-short-maps-on-cauchy-approximations-pseudometric-spaces.lagda.md.

The conventional way to name such files in agda-unimath is e.g. action-on-cauchy-approximations-of-isometries-pseudometric-spaces. This also mirrors how the basic definitions themselves are named, e.g., map-cauchy-approximation-isometry-Pseudometric-Space I guess

@@ -0,0 +1,143 @@
# The action of isometries on Cauchy approximations in pseudometric spaces
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# The action of isometries on Cauchy approximations in pseudometric spaces
# The action on Cauchy approximations of isometries between pseudometric spaces

@@ -0,0 +1,92 @@
# The action of short maps on Cauchy approximations in metric spaces
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# The action of short maps on Cauchy approximations in metric spaces
# The action on Cauchy approximations of short maps between metric spaces

@@ -0,0 +1,97 @@
# The action of short maps on Cauchy approximations in pseudometric spaces
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# The action of short maps on Cauchy approximations in pseudometric spaces
# The action on Cauchy approximations of short maps between pseudometric spaces

( metric-quotient-Pseudometric-Space M))
short-map-metric-quotient-cauchy-apprtoximation-Pseudometric-Space =
short-map-short-function-cauchy-approximation-Pseudometric-Space
short-map-cauchy-approximation-short-function-Pseudometric-Space
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this highlights that short-function should be renamed to short-map

( is-limit-map-lim-cauchy-pseudocompletion-is-complete-Metric-Space u)
```

### The isometry from the Cauchy pseudocompletion of a complete metric space to its limit
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This sentence doesn't make sense. There is no "map" from a complete metric space to its limit. What you exhibit an isometry between is the two

      ( cauchy-pseudocompletion-Metric-Space M)
      ( pseudometric-Metric-Space M)

Comment on lines +34 to +37
[pseudometric spaces](metric-spaces.pseudometric-spaces.md) act on their
[cauchy approximations](metric-spaces.cauchy-approximations-pseudometric-spaces.md)
and induce a short map between their
[Cauchy pseudocompletions](metric-spaces.cauchy-pseudocompletion-of-pseudometric-spaces.md).
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Suggested change
[pseudometric spaces](metric-spaces.pseudometric-spaces.md) act on their
[cauchy approximations](metric-spaces.cauchy-approximations-pseudometric-spaces.md)
and induce a short map between their
[Cauchy pseudocompletions](metric-spaces.cauchy-pseudocompletion-of-pseudometric-spaces.md).
[pseudometric spaces](metric-spaces.pseudometric-spaces.md) act on
[cauchy approximations](metric-spaces.cauchy-approximations-pseudometric-spaces.md)
and induce a short map between the
[Cauchy pseudocompletions](metric-spaces.cauchy-pseudocompletion-of-pseudometric-spaces.md).

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action-on-cauchy-approximations-short-maps-pseudometric-spaces

Comment on lines +32 to +36
[Short maps](metric-spaces.short-functions-metric-spaces.md) between
[metric spaces](metric-spaces.metric-spaces.md) act on their
[cauchy approximations](metric-spaces.cauchy-approximations-metric-spaces.md)
and induce a short map between their
[Cauchy pseudocompletions](metric-spaces.cauchy-pseudocompletion-of-metric-spaces.md).
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Suggested change
[Short maps](metric-spaces.short-functions-metric-spaces.md) between
[metric spaces](metric-spaces.metric-spaces.md) act on their
[cauchy approximations](metric-spaces.cauchy-approximations-metric-spaces.md)
and induce a short map between their
[Cauchy pseudocompletions](metric-spaces.cauchy-pseudocompletion-of-metric-spaces.md).
[metric spaces](metric-spaces.metric-spaces.md) act on
[cauchy approximations](metric-spaces.cauchy-approximations-metric-spaces.md)
and induce a short map between the
[Cauchy pseudocompletions](metric-spaces.cauchy-pseudocompletion-of-metric-spaces.md).

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action-on-cauchy-approximations-short-maps-metric-spaces.lagda.md

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action-on-cauchy-approximations-isometries-pseudometric-spaces.lagda.md

Comment on lines +34 to +38
[Isometries](metric-spaces.isometries-pseudometric-spaces.md) between
[pseudometric spaces](metric-spaces.pseudometric-spaces.md) act on their
[Cauchy approximations](metric-spaces.cauchy-approximations-pseudometric-spaces.md)
and induce an isometry between their
[Cauchy pseudocompletions](metric-spaces.cauchy-pseudocompletion-of-pseudometric-spaces.md).
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Suggested change
[Isometries](metric-spaces.isometries-pseudometric-spaces.md) between
[pseudometric spaces](metric-spaces.pseudometric-spaces.md) act on their
[Cauchy approximations](metric-spaces.cauchy-approximations-pseudometric-spaces.md)
and induce an isometry between their
[Cauchy pseudocompletions](metric-spaces.cauchy-pseudocompletion-of-pseudometric-spaces.md).
[Isometries](metric-spaces.isometries-pseudometric-spaces.md) between
[pseudometric spaces](metric-spaces.pseudometric-spaces.md) act on
[Cauchy approximations](metric-spaces.cauchy-approximations-pseudometric-spaces.md)
and induce an isometry between the
[Cauchy pseudocompletions](metric-spaces.cauchy-pseudocompletion-of-pseudometric-spaces.md).

```agda
{-# OPTIONS --lossy-unification #-}

module metric-spaces.cauchy-approximations-in-cauchy-pseudocompletions-of-pseudometric-spaces where
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module metric-spaces.cauchy-approximations-in-cauchy-pseudocompletions-of-pseudometric-spaces where
module
metric-spaces.cauchy-approximations-in-cauchy-pseudocompletions-of-pseudometric-spaces
where

( map-lim-cauchy-approximation-cauchy-pseudocompletion-Pseudometric-Space ,
is-cauchy-map-lim-cauchy-approximation-cauchy-pseudocompletion-Pseudometric-Space)

is-limit-lim-cauchy-approximation-cauchy-pseudocompletion-Pseudometric-Space :
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seems like it should be marked abstract

in
map-cauchy-approximation-cauchy-pseudocompletion-Pseudometric-Space d₂ d₁

is-cauchy-map-lim-cauchy-approximation-cauchy-pseudocompletion-Pseudometric-Space :
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seems like this should be marked abstract

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Since you're already taking the opportunity to fix some names across the board, would you be so kind to also change the naming pattern short-function- to short-map-?

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