Combinatorial analysis Combinatorial enumeration problems Commutative algebra Mathematics Combinatorics Discrete Mathematics Euler's numbers MATHEMATICS Partitions (Mathematics) Algebraic aspects of posets Algebraic combinatorics Arithmetic rings and other special rings Arrangements of points, flats, hyperplanes Catalan numbers (Mathematics) Combinatorial properties (number of faces, shortest paths, etc.) Combinatorics of partially ordered sets Convex and discrete geometry Designs and configurations Discrete geometry Enumerative combinatorics Exact enumeration problems, generating functions Lattice polytopes (including relations with commutative algebra and algebraic geometry) Mathematicians Matrices Matroids, geometric lattices Order, lattices, ordered algebraic structures Ordered sets Polytopes and polyhedra Problèmes combinatoires d'énumération Shellability