//! The user-implemented `Problem` trait.
use crateEvaluation;
use crateObjectiveSpace;
/// An optimization problem.
///
/// Implement this trait to describe what the optimizer is allowed to vary
/// (`Decision`), how many objectives it has (`objectives`), and how to score a
/// decision (`evaluate`).
///
/// Example decision types: `Vec<f64>`, `Vec<bool>`, `Vec<i64>`, custom domain
/// structs, or permutations represented as `Vec<usize>`.