feat(Order/ConditionallyCompleteLattice): ConditionallyCompleteSemiLatticeInf

[Jun2M]

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[mathlib-bors]

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[github-actions]

PR summary 9036ce5439

Import changes for modified files

No significant changes to the import graph

Import changes for all files

Files	Import difference

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Declarations diff

+ ConditionallyCompleteSemiLatticeInf
+ ConditionallyCompleteSemiLatticeInfTop
+ ConditionallyCompleteSemiLatticeSup
+ ConditionallyCompleteSemiLatticeSupBot
+ OrderDual.instConditionallyCompleteSemiLatticeSup
+ conditionallyCompleteSemiLatticeInfOfsInf
+ conditionallyCompleteSemiLatticeInfOfsInfTop
+ instance [ConditionallyCompleteLinearOrderBot α] : ConditionallyCompleteSemiLatticeSupBot α
+ isGLB_csInf
- isLUB_csSup

You can run this locally as follows

## summary with just the declaration names:
./scripts/pr_summary/declarations_diff.sh <optional_commit>

## more verbose report:
./scripts/pr_summary/declarations_diff.sh long <optional_commit>

The doc-module for scripts/pr_summary/declarations_diff.sh contains some details about this script.

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No changes to technical debt.

You can run this locally as

./scripts/reporting/technical-debt-metrics.sh pr_summary

• The relative value is the weighted sum of the differences with weight given by the inverse of the current value of the statistic.
• The absolute value is the relative value divided by the total sum of the inverses of the current values (i.e. the weighted average of the differences).

[vihdzp]

The design looks reasonable to me, but do you have any examples of structures that would fit these instances?

[vihdzp]

Suggested change

	class ConditionallyCompleteSemiLatticeSup (α : Type*) extends SemilatticeSup α, SupSet α where
	class ConditionallyCompleteSemilatticeSup (α : Type*) extends SemilatticeSup α, SupSet α where

[vihdzp]

Suggested change

	@[to_dual]
	@[to_dual existing]

[vihdzp]

You could get rid of this by adding a requirement to conditionally complete (semi)lattices that if they have a bottom/top, then the supremum/infimum of the empty set equals to it. I think that'd be a worthwhile refactor which can be done independently of adding these semilattice instances.