Publications / zero-rotatability-25-edge-arm-spiders

Zero-rotatability for spiders with 25-edge arms

For every n ≥ 2 and m ≥ 0, every actual vertex of S(25^n,1^m) can receive zero in a graceful labeling, with a separate labeling for each selected vertex.

Let S(25^n,1^m) be the spider with n named arms of 25 edges each and m original unit leaves attached to the center. For every n ≥ 2 and m ≥ 0, each actual vertex—the center, every depth from 1 through 25 on every named arm, and each original center leaf when present—can be assigned zero in a graceful labeling. The labeling may depend on the selected vertex.

The construction combines explicit graceful alpha-labelings of 51-vertex paths with the classical alpha-amalgamation operation. A residual labeling completes the other arms and leaves; separate constructions cover the center, original leaves, and arm endpoints.

Earlier work covers the complete path cases n = 2, m = 0 and n = 2, m = 1; Luiz, Campos, and Richter's Theorem 14 treats a path with one center leaf. Shan and Zhong restate the classical alpha-amalgamation operation used in the transfer. The full fixed-k25 statement is supported by internal mathematical checks and a separate copied-source Lean replay. The bounded comparison does not settle whether earlier constructions subsume the full statement, so historical priority remains unknown.

Statements & evidence

K25-ALL-ACTUAL-VERTEX-ZERO-ROTATABILITY Proof provided

For every integer n ≥ 2, every integer m ≥ 0, and every actual vertex v of S(25^n,1^m), there exists a graceful labeling f of that graph with f(v)=0. The labeling may depend on v.

Formal verification
Formally verified within the stated scope
Review status
Internal check
Evidence
Independent mathematical/graph QA report SHA-256 315907b9cb57d5449de00172b2d1d3b4df80aa3013813303a843c405b4563771; author formal freeze report SHA-256 cdd8ce2cb2a393fc6d4ec4734f6f68ae59cb4c47f1b46e7794080fd768523c01; copied-source Lean replay report SHA-256 07bf8eb86738caae8701b34fd1bef5683544a3650c2125f606ca4ae5feb9b5a6; bounded priority comparison report SHA-256 80d1ea284b6cc9fdb0b4bad0b680b9b678859d41d653678b531346ede3211b2d.
Scope
For every n ≥ 2 and m ≥ 0, every actual named vertex of S(25^n,1^m): its center, each depth 1 through 25 on every named arm, and each of its m original center leaves when present. A possibly different graceful labeling is supplied for each selected vertex. The graph has 25n+m edges; vertex labels are 0..25n+m and edge weights are 1..25n+m.
Assumptions
S(25^n,1^m) is the finite spider with n named arms of exactly 25 edges each and m original unit leaves attached to the center. A graceful labeling is a bijection from vertices to 0 through |E| and induces a bijection from edges to 1 through |E| by absolute endpoint differences. Every selected vertex is handled separately.
Toolchain
Lean 4.34.0; 27 fixed-k25 modules freshly compiled with -DwarningAsError=true in author freeze and separate copied-source replay; theorem GracefulBoundary.K25Full.all_vertices; internal mathematical/graph QA. Standard Lean kernel verification.
Reviewer
Internal mathematical/graph QA and separate copied-source Lean replay only; no external or peer review is claimed.

Files & reproduction

No files attached.

Contributions & AI assistance

Contributions

Jordi Gartner publishes this work through Beedbyte.

AI assistance

Methods: AI tools assisted with developing the construction, formalizing and checking the proof, and comparing earlier sources; Lean 4.34.0 verifies the frozen theorem.

References

  1. Fixed-k25 versioned source package (commit-pinned)
  2. Fixed-k25 package README (commit-pinned)
  3. English research note (commit-pinned)
  4. German draft translation (commit-pinned)
  5. Simplified Chinese draft translation (commit-pinned)
  6. Lean theorem source: K25Full.lean (commit-pinned)
  7. Luiz, Campos, and Richter, technical report IC-17-12 (Rosa path result and Theorem 14).
  8. Shan and Zhong, Graceful Labeling of Two Families of Spiders, Lemma 1 (classical alpha-amalgamation statement).

Version history

VersionPublishedChange note
v1Proves zero-rotatability for every actual vertex of S(25^n,1^m) for n ≥ 2 and m ≥ 0, with a separate graceful labeling for each selected vertex.

Cite this version

Beedbyte. Zero-rotatability for spiders with 25-edge arms. Beedbyte, v1, 2026-10-10.

https://beedbyte.tech/publications/zero-rotatability-25-edge-arm-spiders/v/1

SHA-256 — Version73bda8d01a59567ceee1112ad4020e2c691c8e1e3e960cb01d138997ab7fbdd3

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