The Balanced Two-Block Family
Abstract
The balanced decreasing-block word satisfies the required avoidance conditions.
Theorem 1.1 (Avoidance by the balanced word and its images).
Lean statement: D5/S3/Combinatorics/FundamentalBijection/ThetaIterateWTests.W_tests
Proof. Machine-checked in Lean as D5/S3/Combinatorics/FundamentalBijection/ThetaIterateWTests.W_tests (✓ std3). ∎
Source. Repository-derived.
Acknowledgement. Kassie Archer, Robert P. Laudone (2024). Pattern avoidance and the fundamental bijection. DOI: 10.48550/arXiv.2407.06338. URL: https://arxiv.org/abs/2407.06338v1.
Commentary.
For h at least four, W(h) permutes one through h, and W(h), b(W(h)), and the fundamental image of W(h) all avoid 132; consequently P(W(h)) avoids 132 through depth two.
References
- Truth anchor:
D5/S3/Combinatorics/FundamentalBijection/ThetaIterateWTests.W_tests - Dependency: D5/S3/Combinatorics/FundamentalBijection/ThetaIterateCycleReduction
- Dependency: D5/S3/Combinatorics/FundamentalBijection/ThetaIterateForcedWord