
CHAPTER 2
Methods and Models
ABSTRACT
Modeling methods appropriate to the study of combinatorial aspects
arising in high complexity problems as differential posets, dual graded
graphs, updown categories and combinatorial species are presented. The
polytope representations, grounded on n-levels systems theories, represent
a natural development of the previous methods. Generic models capture
the intuition of the elementary differential calculus and develop calculus
for polytope projects.
Keywords: combinatorics, commutation, differential posets, dual graded
graphs, generating series, generic model, integration, lattice, polytope,
posets, species, ...