The Wagner-Whitin table gives not just a cost but an order plan. Traceback names the order periods and quantities, then the baselines show what the plan improves on.
highlighted = computed this step
Traceback Plan
The first order is in period 1 for quantity 6, covering periods 1 through 3. Motivation: traceback turns the DP predecessor row into an order that covers a whole prefix block.
order period 1q=6
Final Order
The second order is in period 4 for quantity 4. Why: the final period is cheapest as its own order in this instance.
order period 4q=4
Rival Policies
The Wagner-Whitin cost is 15, ordering every period costs 20, and ordering once costs 22. Interpretation: the DP proves the chosen plan beats these two simple rivals for the pinned demand.
15<20<22
Diagram note
Honesty note: Wagner-Whitin is exact for this pinned finite discrete demand instance. Pixel positions are rounded for layout; every number shown is exact.