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What is Meant by an Optimal Solution?

Published in Optimization 3 mins read

An optimal solution represents the best possible outcome in a given problem, where the goal is to maximize or minimize a specific value.

Based on the reference provided, an optimal solution is a feasible solution where the objective function reaches its maximum (or minimum) value – for example, aiming for the most profit or the least cost.

Understanding the Key Components

To fully grasp what an optimal solution means, it's helpful to break down the definition:

  • Feasible Solution: This is any solution that satisfies all the constraints or requirements of the problem. Think of it as a valid way to do something within the rules.
  • Objective Function: This is the mathematical expression you want to maximize or minimize. It represents the goal you're trying to achieve (e.g., profit, cost, time, resource usage).
  • Maximum/Minimum Value: Depending on the problem, the optimal solution will either achieve the highest possible value (like maximum profit) or the lowest possible value (like minimum cost) for the objective function among all feasible solutions.

Globally Optimal vs. Local Optimal

The reference also mentions a specific type of optimal solution:

  • Globally Optimal Solution: This is the absolute best feasible solution across the entire problem space. The reference states, "A globally optimal solution is one where there are no other feasible solutions with better objective function values." This means no other valid option exists that yields a better result for your objective function.

While not explicitly in the provided reference, it's worth noting that in complex problems, there can also be local optimal solutions, which are the best within a limited range of feasible solutions but not necessarily the best overall. The definition provided focuses on the global optimum.

Practical Examples

Consider these scenarios to illustrate the concept:

  • Business Profit: A company wants to decide production quantities for various products.
    • Objective Function: Maximize total profit.
    • Feasible Solutions: Any production plan that doesn't exceed available resources (labor, materials, machine time).
    • Optimal Solution: The specific production plan that yields the highest possible profit while staying within resource limits.
  • Logistics Cost: A delivery service needs to plan routes for its trucks.
    • Objective Function: Minimize total distance or fuel cost.
    • Feasible Solutions: Any valid set of routes that covers all deliveries.
    • Optimal Solution: The route plan that results in the lowest total distance or fuel cost among all possible valid plans.

Why Optimal Solutions Matter

Finding the optimal solution is crucial in many fields like operations research, economics, engineering, and computer science because it helps organizations and individuals make the best possible decisions given their constraints and goals. It moves beyond simply finding a good solution to finding the absolute best one.

Term Definition Goal for Objective Function
Feasible Solution Satisfies all constraints N/A
Optimal Solution A feasible solution achieving the max or min value of the objective function Max or Min
Globally Optimal An optimal solution that is the absolute best among all feasible solutions Absolute Max or Min

In summary, an optimal solution is the peak (or trough) of performance within the bounds of possibility, ensuring the most desired outcome for the specific objective.