Bidirectional Algorithms for Polygon Triangulations and (m + 2)-Angulations via Fuss–Catalan Numbers
Aybeyan Selimi, Muzafer H Saracevic, Lazar V. Stošić, Ömer Aydın, Mahir Zajmović · Mathematics · 2025
Polygon triangulations and their generalizations to m+2−angulations are fundamental in combinatorics and computational geometry. This paper presents a unified linear-time framework that establishes explicit bijections between m−Dyck words, planted m+1−ary trees, and m+2−angulations of convex polygons. We introduce stack-based and tree-based algorithms that enable reversible conversion between symbolic and geometric representations, prove their correctness and optimal complexity, and demonstrate their scalability through extensive experiments. The approach reveals a hierarchical decomposition encoded by Fuss–Catalan numbers, providing a compact and uniform representation for triangulations, quadrangulations, pentangulations, and higher-arity angulations. Experimental comparisons show clear advantages over rotation-based methods in both runtime and memory usage. The framework offers a general combinatorial foundation that supports efficient enumeration, compressed representation, and extensions to higher-dimensional or non-convex settings.