A sequencing problem is a scheduling problem where you decide the best order to do tasks or jobs so you can minimize time, cost, delays, or other penalties. In operations research, it often means arranging jobs on one or more machines in the most efficient sequence.

Quick Scoop

A sequencing problem asks: “In what order should tasks be done?” The answer matters because different orders can change the total completion time, idle time, lateness, or cost.

Common examples include:

  • Jobs in a manufacturing plant.
  • Aircraft waiting to land.
  • Computer programs or CPU jobs.
  • Customers being served in a bank.

Why It Matters

The goal is not just to finish the work, but to finish it efficiently. A good sequence can reduce wasted machine time, lower delays, and improve productivity.

Simple Example

If three jobs must be processed on a machine, the order A→C→BA\rightarrow C\rightarrow BA→C→B may finish faster than B→A→CB\rightarrow A\rightarrow CB→A→C. That is the core idea of sequencing: the order changes the outcome.

In Operations Research

Sequencing problems are a major topic in operations research and include cases like:

  • One machine with many jobs.
  • Two machines.
  • Three or more machines.
  • Flow shop and job scheduling settings.

A well-known method used in some two-machine cases is Johnson’s rule.

If you want, I can also explain it in very simple exam-style language or give a worked example.