[Merged by Bors] - feat(Combinatorics/SimpleGraph): define odd components

[pimotte]

Adds the definition oddComponents: The set of connected components of odd cardinality.
In preparation for Tutte's theorem.

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Zulip thread on Tutte's

[github-actions]

PR summary 9ad99587a3

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

+ ConnectedComponent.odd_oddComponents_ncard_subset_supp
+ ncard_oddComponents_mono
+ oddComponents
+ odd_ncard_oddComponents
- ConnectedComponent.odd_card_supp_iff_odd_subcomponents
- ncard_odd_components_mono
- odd_card_iff_odd_components

You can run this locally as follows

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

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

The doc-module for script/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/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).

[YaelDillies]

Thanks!

maintainer delegate

[github-actions]

🚀 Pull request has been placed on the maintainer queue by YaelDillies.

[b-mehta]

Thanks!

bors merge

[mathlib-bors]

Pull request successfully merged into master.

Build succeeded:

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