[Becheler]

Fixes #182

Motivation

tiernan_all_cycles asserted VertexIndexGraphConcept, which requires renumber_vertex_indices(). Only directed_graph and undirected_graph provide that function, so the algorithm failed to compile for every other graph type, including adjacency_list. The algorithm never calls renumber_vertex_indices(). It only reads vertex indices.

What this PR does

Replaces the check with one that only requires a readable vertex_index map, which is what the documentation already states. tiernan_all_cycles now compiles for adjacency_list and any other graph with a vertex_index map. A new regression test runs the algorithm on an adjacency_list and expects two cycles.

Before submitting

• I searched for an existing PR or issue covering the same change.
• This PR targets the develop branch.
• My contribution is licensed under the Boost Software License 1.0.

Kind of change

Tick exactly one. Each kind is reviewed differently, so mixing them in one PR makes the diff difficult to review (why).

• Reformat (layout only, no token added or removed)
• Refactor (no observable behavior change)
• Behavior change (observable to users of the library)
• No code change (documentation, build, CI, or tooling)

Change category

• Bug fix
• New algorithm or API addition
• Deprecation or removal
• Performance
• Tests
• Documentation
• Build, CI, or tooling
• Other (specify below)

[github-actions]

Boost dependency footprint vs develop (auto-generated).
PR run 41295751839 vs develop run 41229730759 (7844c670ac).

Header-inclusion weights (graph files pulling each direct dependency in):

No header-inclusion-weight changes.

Transitive Boost modules: 47 → 47 (0)

[github-actions]

Compiler-warning counts vs develop (auto-generated).
PR run 41295751841 vs develop run 41229730419 (7844c670ac).

Job	Baseline	After	Delta
macos (clang, 14)	260	260	0
macos (clang, 17)	259	259	0
macos (clang, 20)	259	259	0
ubuntu (clang-19, 14)	260	260	0
ubuntu (clang-19, 17)	259	259	0
ubuntu (clang-19, 20)	259	259	0
ubuntu (clang-19, 23)	259	259	0
ubuntu (gcc-14, 14)	361	361	0
ubuntu (gcc-14, 17)	357	357	0
ubuntu (gcc-14, 20)	357	357	0
ubuntu (gcc-14, 23)	357	357	0
windows_msvc_14_3 (msvc-14.3)	961	955	-6

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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