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[Merged by Bors] - feat(order/lattice): add complete_semilattice_Sup/Inf #6797

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This adds complete_semilattice_Sup and complete_semilattice_Inf above complete_lattice.

This has not much effect, as in fact either implies complete_lattice. However it's useful at times to have these, when you can naturally define just one half of the structure at a time (e.g. the subobject lattice in a general category, where for Sup we need coproducts and images, while for the Inf we need wide pullbacks).

There are many places in mathlib that currently use complete_lattice_of_Inf. It might be slightly nicer to instead construct a complete_semilattice_Inf, and then use the new complete_lattice_of_complete_semilattice_Inf, but I haven't done that here.


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@semorrison semorrison added the awaiting-review The author would like community review of the PR label Mar 21, 2021
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Co-authored-by: Bryan Gin-ge Chen <bryangingechen@gmail.com>
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Looks reasonable to me

bors d+

Probably worth merging master ifrst just in case this has gone stale, unless bors is idle anyway

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bors bot commented Mar 26, 2021

✌️ semorrison can now approve this pull request. To approve and merge a pull request, simply reply with bors r+. More detailed instructions are available here.

@bryangingechen bryangingechen added delegated The PR author may merge after reviewing final suggestions. and removed awaiting-review The author would like community review of the PR labels Mar 26, 2021
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bors merge

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bors bot commented Mar 26, 2021

Canceled.

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bors merge

@github-actions github-actions bot added the ready-to-merge All that is left is for bors to build and merge this PR. (Remember you need to say `bors r+`.) label Mar 26, 2021
bors bot pushed a commit that referenced this pull request Mar 26, 2021
This adds `complete_semilattice_Sup` and `complete_semilattice_Inf` above `complete_lattice`.

This has not much effect, as in fact either implies `complete_lattice`. However it's useful at times to have these, when you can naturally define just one half of the structure at a time (e.g. the subobject lattice in a general category, where for `Sup` we need coproducts and images, while for the `Inf` we need wide pullbacks).

There are many places in mathlib that currently use `complete_lattice_of_Inf`. It might be slightly nicer to instead construct a `complete_semilattice_Inf`, and then use the new `complete_lattice_of_complete_semilattice_Inf`, but I haven't done that here.



Co-authored-by: Scott Morrison <scott.morrison@gmail.com>
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bors bot commented Mar 26, 2021

Canceled.

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bors merge

bors bot pushed a commit that referenced this pull request Mar 27, 2021
This adds `complete_semilattice_Sup` and `complete_semilattice_Inf` above `complete_lattice`.

This has not much effect, as in fact either implies `complete_lattice`. However it's useful at times to have these, when you can naturally define just one half of the structure at a time (e.g. the subobject lattice in a general category, where for `Sup` we need coproducts and images, while for the `Inf` we need wide pullbacks).

There are many places in mathlib that currently use `complete_lattice_of_Inf`. It might be slightly nicer to instead construct a `complete_semilattice_Inf`, and then use the new `complete_lattice_of_complete_semilattice_Inf`, but I haven't done that here.



Co-authored-by: Scott Morrison <scott.morrison@gmail.com>
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bors bot commented Mar 27, 2021

Pull request successfully merged into master.

Build succeeded:

@bors bors bot changed the title feat(order/lattice): add complete_semilattice_Sup/Inf [Merged by Bors] - feat(order/lattice): add complete_semilattice_Sup/Inf Mar 27, 2021
@bors bors bot closed this Mar 27, 2021
@bors bors bot deleted the complete_semilattice_Sup branch March 27, 2021 06:35
b-mehta pushed a commit that referenced this pull request Apr 2, 2021
This adds `complete_semilattice_Sup` and `complete_semilattice_Inf` above `complete_lattice`.

This has not much effect, as in fact either implies `complete_lattice`. However it's useful at times to have these, when you can naturally define just one half of the structure at a time (e.g. the subobject lattice in a general category, where for `Sup` we need coproducts and images, while for the `Inf` we need wide pullbacks).

There are many places in mathlib that currently use `complete_lattice_of_Inf`. It might be slightly nicer to instead construct a `complete_semilattice_Inf`, and then use the new `complete_lattice_of_complete_semilattice_Inf`, but I haven't done that here.



Co-authored-by: Scott Morrison <scott.morrison@gmail.com>
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