Groff lot-sizing rule

Public class: GroffSolver.

Reference:

G. K. Groff (1979), A Lot-Sizing Rule for Time-Phased Component Demand, Production and Inventory Management 20(1), 47-53.

For a cycle beginning at t, demand at offset n is included while

\[d_{t+n}\,n(n+1)\leq \frac{2A}{h}. \]

The rule is a marginal-cost approximation derived from the setup/holding trade-off. It scans each generated cycle forward and returns a feasible, non-optimal ULS solution.