Struct LiftProjectMipSolver 

pub struct LiftProjectMipSolver { /* private fields */ }

Lift-and-project cut manager for MIP solving.

Maintains a pool of previously generated cuts so they can be re-used across branch-and-cut nodes without regenerating them from scratch.

Implementations

impl LiftProjectMipSolver

pub fn new(config: LiftProjectConfig) -> Self

Create a new solver with the given configuration.

pub fn default_solver() -> Self

Create a solver with default configuration.

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

Generate lift-and-project cuts violated at x_bar and add them to the pool.

Arguments

• a – Constraint matrix rows (a[i][k] is the coefficient of x_k in row i). The constraint is a[i] · x ≤ b[i].
• b – Right-hand side.
• x_bar – Current LP relaxation solution.
• integer_vars – Indices of variables constrained to {0, 1}.

Returns

The newly generated cuts that are violated at x_bar. These have already been added to the internal cut pool; the caller should augment the LP with these cuts and re-solve.

pub fn cut_pool_size(&self) -> usize

Number of cuts currently in the pool.

pub fn cut_pool(&self) -> &[LiftProjectCut]

Access the full cut pool (read-only).

pub fn clear_cut_pool(&mut self)

Remove all cuts from the pool (e.g., when moving to a new B&B node).

pub fn purge_non_violated_cuts(&mut self, x_new: &[f64])

Retain only cuts that are still violated at a new LP solution x_new.

This is useful for node-level cut management: cuts that were valid at the parent node but are no longer violated can be removed to keep the working LP compact.

pub fn iterations(&self) -> usize

Number of times add_cuts_to_lp has been called.

pub fn total_cuts_generated(&self) -> usize

Cumulative count of all cuts ever generated (including purged ones).

pub fn config(&self) -> &LiftProjectConfig

Read-only reference to the underlying configuration.

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

Compute the violation of a cut at x_bar.

Returns π · x_bar - π₀. Positive means x_bar violates the cut.

pub fn build_augmented_system( &self, a: &[Vec<f64>], b: &[f64], ) -> OptimizeResult<(Vec<Vec<f64>>, Vec<f64>)>

Build an augmented constraint system by appending pooled cuts to (a, b).

The BCC cuts are stored as π · x ≥ π₀. To express them in ≤ form for standard LP solvers, we negate: −π · x ≤ −π₀.

Returns

(a_aug, b_aug) where the first a.len() rows are the original constraints and the subsequent rows are the negated cut inequalities.