Abstract
Harary et al. put forward the concept on the minimum cardinality over all subsets of perfect matching \(M\) that are not included by any other ones, to be the forcing number for \(M\). A counting polynomial for perfect matchings possessing the same forcing
number was introduced by Zhang et al., using the name `forcing polynomial'. This research deduces recurrence formulas of forcing polynomials for monotonic constructable hexagonal systems and constructable hexagonal systems with one turning.
From them, a characterization of continuity of forcing spectrum for hexagonal systems with forcing edges can be derived.
