Struct LiftProjectGenerator 

pub struct LiftProjectGenerator { /* private fields */ }

Generator for Balas-Ceria-Cornuéjols lift-and-project cuts.

Usage

use scirs2_optimize::integer::lift_project::{
    LiftProjectConfig, LiftProjectGenerator,
};

let config = LiftProjectConfig::default();
let gen = LiftProjectGenerator::new(config);

// Constraint: x1 + x2 <= 1, x1 >= 0, x2 >= 0, x1,x2 ∈ {0,1}
let a = vec![vec![1.0, 1.0]];
let b = vec![1.0];
let x_bar = vec![0.6, 0.4]; // fractional LP solution
let integer_vars = vec![0, 1];

let cuts = gen.generate_cuts(&a, &b, &x_bar, &integer_vars).unwrap();
assert!(!cuts.is_empty());

Implementations

impl LiftProjectGenerator

pub fn new(config: LiftProjectConfig) -> Self

Create a new generator with the given configuration.

pub fn default_generator() -> Self

Create a new generator with default configuration.

pub fn generate_cuts( &self, a: &[Vec<f64>], b: &[f64], x_bar: &[f64], integer_vars: &[usize], ) -> OptimizeResult<Vec<LiftProjectCut>>

Generate lift-and-project cuts from the LP relaxation solution.

Arguments

• a – Constraint matrix rows (constraint is a[i] · x ≤ b[i]).
• b – Right-hand side vector.
• x_bar – Current LP relaxation solution (may be fractional).
• integer_vars – Indices of variables constrained to {0, 1}.

Returns

A vector of LiftProjectCuts violated at x_bar, sorted by decreasing violation (strongest cut first). Empty when x_bar is integer-feasible.

pub fn select_variable( &self, x_bar: &[f64], integer_vars: &[usize], ) -> Option<usize>

Select a single fractional variable according to the configured strategy.

Returns None if no fractional variable is found among integer_vars.

pub fn generate_cut_for_var( &self, a: &[Vec<f64>], b: &[f64], x_bar: &[f64], j: usize, ) -> Option<LiftProjectCut>

Generate the single strongest BCC disjunctive cut for fractional variable j.

Uses the augmented constraint system (structural + bound rows) to ensure a violated cut can always be found when x̄_j ∈ (0, 1).

Returns None when:

• x̄_j is integer-valued (within int_tol), or
• No row in the augmented system gives violation > cut_violation_tol.

pub fn cut_violation(&self, cut: &LiftProjectCut, x_bar: &[f64]) -> f64

Compute the signed violation of a cut at x̄.

Returns π · x̄ - π₀. A positive value means x̄ violates the cut (x̄ does not satisfy π · x ≥ π₀). A negative or zero value means x̄ satisfies it.