ZZ Polynomials of Regular m-tier Benzenoid Strips as Extended Strict Order Polynomials of Associated Posets Part 2. Guide to Practical Computation

We present an algorithm for computing the ZZ polynomial of an arbitrary m-tier regular strip of length n. Our approach is based on the equivalence between the ZZ polynomial ZZ(S, x) of a regular benzenoid strip S and the extended strict order polynomial E^◦_S(n, 1 + x) of the corresponding poset S, demonstrated formally in Part 1 of the current series of papers. The process of computing ZZ(S, x) in the form of E^◦_S(n, 1 + x) reduces to four, fully automatable steps: (i) Construction of the poset S corresponding to S. (ii) Construction of the Jordan-Hölder set L(S) of linear extensions of S. (iii) Computing the number des(w) of descents in each w ∈ L(S). (iv) Computing the number fix_S(w) of fixed labels in each w ∈ L(S). The ZZ polynomial of S can then be expressed in the following form ∑ w∈L(S₎^∑_k^|S|₌₀⁽|S| _k − ₋ fix _{fix S S} (₍w _w ) ₎⁾⁽n + des(_k w)⁾ (1 + x_)k, ZZ(S, x) = E^◦_S(n, 1 + x) = where |S| denotes the number of elements in S. Practical applications of the algorithm are illustrated with a few examples. The complete account of ZZ polynomials of regular m-tier benzenoid strips S with m = 1–6 computed using the introduced algorithm is presented in Part 3 of the current series of papers.