Turning a described situation into a model somebody can solve, and the discrete decision problems where the requirement to choose whole units is the whole difficulty: the LP relaxation and why rounding it fails, integer programming, branch and bound, binary variables for logical conditions, then transportation, knapsack, set covering, facility location and bin packing. It closes with the classical inventory and scheduling models: economic order quantity, the newsvendor, safety stock, the critical path method, PERT, multiple objectives, and how far the inputs can be wrong before the recommendation changes. Scoped against optimization, graph theory, probability, modeling, game theory and discrete mathematics, which own linear programming and duality, the network algorithms, queueing, Monte Carlo, minimax and approximation hardness respectively.
Free to start · adaptive placement finds your level · reviews timed so it stays learned.
Every idea is taught with motivation and a worked example before the drills, and an FSRS spaced-repetition engine schedules each review for the moment just before you'd forget it. A short placement check finds what you already know, so you start Operations Research exactly where it's useful.