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[Merged by Bors] - feat(Combinatorics/SimpleGraph): hamiltonian graphs don't contain bridges#36802

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[Merged by Bors] - feat(Combinatorics/SimpleGraph): hamiltonian graphs don't contain bridges#36802
YaelDillies wants to merge 5 commits intoleanprover-community:masterfrom
YaelDillies:bridge_not_hamiltonian

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@YaelDillies YaelDillies commented Mar 18, 2026

Replace the longer proof which further assumed that the vertex set has at least three elements.


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@github-actions github-actions bot added the large-import Automatically added label for PRs with a significant increase in transitive imports label Mar 18, 2026
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github-actions bot commented Mar 18, 2026

PR summary 8877189b60

Import changes exceeding 2%

% File
+29.97% Mathlib.Combinatorics.SimpleGraph.Hamiltonian

Import changes for modified files

Dependency changes

File Base Count Head Count Change
Mathlib.Combinatorics.SimpleGraph.Hamiltonian 594 772 +178 (+29.97%)
Import changes for all files
Files Import difference
Mathlib.Combinatorics.SimpleGraph.Hamiltonian 178

Declarations diff

+ IsBridge.nontrivial
+ IsBridge.not_isHamiltonian
+ IsCircuit.of_rotate
+ IsCycle.of_rotate
+ IsHamiltonian.exists_isHamiltonianCycle
+ IsHamiltonian.finite
+ IsHamiltonianCycle.finite
+ IsHamiltonianCycle.of_rotate
+ IsHamiltonianCycle.rotate
+ IsTrail.isEdgeReachable_two
+ IsTrail.isEdgeReachable_two_of_isEdgeReachable_two
+ IsTrail.isEdgeReachable_two_of_isEdgeReachable_two_aux
+ IsTrail.of_rotate
+ isCircuit_rotate
+ isCycle_rotate
+ isHamiltonianCycle_rotate
+ isTrail_rotate
+ length_rotate
+ not_isHamiltonianCycle_of_infinite
+ not_isHamiltonian_of_infinite
+ rotate_eq_nil
- not_isHamiltonian_of_isBridge

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.


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).

@github-actions github-actions bot added the t-combinatorics Combinatorics label Mar 18, 2026
@mathlib-dependent-issues mathlib-dependent-issues bot added the blocked-by-other-PR This PR depends on another PR (this label is automatically managed by a bot) label Mar 18, 2026
@mathlib-dependent-issues mathlib-dependent-issues bot removed the blocked-by-other-PR This PR depends on another PR (this label is automatically managed by a bot) label Mar 18, 2026
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@YaelDillies YaelDillies force-pushed the bridge_not_hamiltonian branch from 65935d2 to 76c1f66 Compare March 18, 2026 15:24
@YaelDillies YaelDillies requested a review from b-mehta March 18, 2026 15:24
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This pull request has conflicts, please merge master and resolve them.

@mathlib-merge-conflicts mathlib-merge-conflicts bot added the merge-conflict The PR has a merge conflict with master, and needs manual merging. (this label is managed by a bot) label Mar 19, 2026
…bridge

Replace the longer proof which assumed that the vertex set has at least three elements.
@YaelDillies YaelDillies force-pushed the bridge_not_hamiltonian branch from 76c1f66 to 88e3a7d Compare March 19, 2026 10:34
@github-actions github-actions bot removed the merge-conflict The PR has a merge conflict with master, and needs manual merging. (this label is managed by a bot) label Mar 19, 2026
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@Rida-Hamadani Rida-Hamadani left a comment

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Is the title meant to be "hamiltonian graphs" instead of "hamiltonians graphs"?

@YaelDillies YaelDillies changed the title feat(Combinatorics/SimpleGraph): hamiltonians graphs don't contain bridges feat(Combinatorics/SimpleGraph): hamiltonian graphs don't contain bridges Apr 1, 2026
@b-mehta b-mehta added the awaiting-author A reviewer has asked the author a question or requested changes. label Apr 1, 2026
@YaelDillies YaelDillies removed the awaiting-author A reviewer has asked the author a question or requested changes. label Apr 1, 2026
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Thanks!

bors merge

mathlib-bors bot pushed a commit that referenced this pull request Apr 1, 2026
…dges (#36802)

Replace the longer proof which further assumed that the vertex set has at least three elements.
@mathlib-triage mathlib-triage bot added the ready-to-merge This PR has been sent to bors. label Apr 1, 2026
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mathlib-bors bot commented Apr 1, 2026

Canceled.

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b-mehta commented Apr 1, 2026

bors merge

mathlib-bors bot pushed a commit that referenced this pull request Apr 1, 2026
…dges (#36802)

Replace the longer proof which further assumed that the vertex set has at least three elements.
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mathlib-bors bot commented Apr 1, 2026

Pull request successfully merged into master.

Build succeeded:

@mathlib-bors mathlib-bors bot changed the title feat(Combinatorics/SimpleGraph): hamiltonian graphs don't contain bridges [Merged by Bors] - feat(Combinatorics/SimpleGraph): hamiltonian graphs don't contain bridges Apr 1, 2026
@mathlib-bors mathlib-bors bot closed this Apr 1, 2026
@YaelDillies YaelDillies deleted the bridge_not_hamiltonian branch April 1, 2026 17:59
xroblot pushed a commit to xroblot/mathlib4 that referenced this pull request Apr 3, 2026
…dges (leanprover-community#36802)

Replace the longer proof which further assumed that the vertex set has at least three elements.
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3 participants