Caterpillar classification conjecture for Penrose caterpillars

Let CC be a Penrose caterpillar, let SS be the graded poset of caterpillars used in the source, and let fboatf_{boat} transform a Penrose caterpillar by replacing each relevant subpath along the hull of a boat with the corresponding subpath along the top of the boat. Write (fboat(C))(f_{boat}(C))' for its derived path. Caterpillar classification conjecture. CC belongs to one of the following two sets:

(i) CC belongs to the graded poset SS.

(ii) There exists a caterpillar CkC_k such that the derived path (fboat(C))(f_{boat}(C))' is included in the derived path (fboat(Ck))(f_{boat}(C_k))', up to isomorphism.

The conjecture is intended to describe the possible shapes of fully leafed Penrose trees through the family of Penrose caterpillars and the boat-path transformation. The source states no result resolving this classification.

Sources & referencesView supporting material

Primary source

Carole Porrier, Alain Goupil and Alexandre Blondin Massé, “The Leaf Function of Penrose P2 Graphs”, arXiv:2312.08262 (2025).

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