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feat(SimpleGraph): Weaker condition for paths in acyclic graphs#25630

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feat(SimpleGraph): Weaker condition for paths in acyclic graphs#25630
vlad902 wants to merge 1 commit intomasterfrom
vlad.tsyrklevich/cg4-istree

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@vlad902 vlad902 commented Jun 9, 2025

IsAcyclic.isPath_iff_chain' defines a weaker condition for proving that a walk is a path, in particular it shows that rather than proving that all vertices in the support of a walk are distinct, one must only show that consecutive edges are distinct (e.g. every other vertex must be distinct.) This leads to a simple corollary that trails are also paths in acyclic graphs.

`IsAcyclic.isPath_iff_chain'` defines a weaker condition for proving
that a walk is a path, in particular it shows that rather than all
vertices in the support of a walk being distinct, one must only show
that consecutive vertices are distinct. This leads to a simple
corollary that trails are paths in acyclic graphs.
@github-actions github-actions bot added the t-combinatorics Combinatorics label Jun 9, 2025
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github-actions bot commented Jun 9, 2025

PR summary b27d4790e1

Import changes for modified files

No significant changes to the import graph

Import changes for all files
Files Import difference

Declarations diff

+ IsAcyclic.isPath_iff_chain'
+ IsAcyclic.isPath_of_isTrail
+ IsPath.eq_penultimate_of_mem_edges
+ IsPath.eq_snd_of_mem_edges

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.


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).

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vlad902 commented Jun 12, 2025

This PR has been migrated to a fork-based workflow: #25814

@vlad902 vlad902 closed this Jun 12, 2025
@YaelDillies YaelDillies deleted the vlad.tsyrklevich/cg4-istree branch August 15, 2025 16:44
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