Struct SpinGlass 

pub struct SpinGlass<G, W> { /* private fields */ }

The Spin Glass (Ising model) problem.

Given n spin variables s_i in {-1, +1}, interaction coefficients J_ij, and on-site fields h_i, minimize the Hamiltonian:

H(s) = sum_{i<j} J_ij * s_i * s_j + sum_i h_i * s_i

Representation

Variables are binary (0 or 1), mapped to spins via: s = 2*x - 1

• x = 0 -> s = -1
• x = 1 -> s = +1

Type Parameters

• G - The graph type (e.g., SimpleGraph, KingsSubgraph, UnitDiskGraph)
• W - The weight type for couplings (e.g., i32, f64)

Example

use problemreductions::models::graph::SpinGlass;
use problemreductions::topology::SimpleGraph;
use problemreductions::{Problem, Solver, BruteForce};

// Two spins with antiferromagnetic coupling J_01 = 1
let problem = SpinGlass::<SimpleGraph, f64>::new(2, vec![((0, 1), 1.0)], vec![0.0, 0.0]);

let solver = BruteForce::new();
let solutions = solver.find_all_best(&problem);

// Ground state has opposite spins
for sol in &solutions {
    assert!(sol[0] != sol[1]); // Antiferromagnetic: opposite spins
}

Implementations

impl<W: Clone + Default> SpinGlass<SimpleGraph, W>

pub fn new( num_spins: usize, interactions: Vec<((usize, usize), W)>, fields: Vec<W>, ) -> Self

Create a new Spin Glass problem.

Arguments

• num_spins - Number of spin variables
• interactions - Coupling terms J_ij as ((i, j), value)
• fields - On-site fields h_i

pub fn without_fields( num_spins: usize, interactions: Vec<((usize, usize), W)>, ) -> Self

where W: Zero,

Create a Spin Glass with no on-site fields.

impl<G: Graph, W: Clone + Default> SpinGlass<G, W>

pub fn from_graph(graph: G, couplings: Vec<W>, fields: Vec<W>) -> Self

Create a SpinGlass problem from a graph with specified couplings.

Arguments

• graph - The underlying graph
• couplings - Coupling terms (must match graph.num_edges())
• fields - On-site fields h_i

pub fn from_graph_without_fields(graph: G, couplings: Vec<W>) -> Self

where W: Zero,

Create a SpinGlass problem from a graph with no on-site fields.

pub fn graph(&self) -> &G

Get a reference to the underlying graph.

pub fn num_spins(&self) -> usize

Get the number of spins.

pub fn num_interactions(&self) -> usize

Get the number of interactions (edges in the interaction graph).

pub fn interactions(&self) -> Vec<((usize, usize), W)>

Get the interactions as ((i, j), weight) pairs.

Reconstructs from graph.edges() and couplings.

pub fn couplings(&self) -> &[W]

Get the couplings (J_ij values).

pub fn fields(&self) -> &[W]

Get the on-site fields.

pub fn config_to_spins(config: &[usize]) -> Vec<i32>

Convert binary config (0,1) to spin config (-1,+1).

impl<G, W> SpinGlass<G, W>

where G: Graph, W: Clone + Zero + AddAssign + Mul<Output = W> + From<i32>,

pub fn compute_energy(&self, spins: &[i32]) -> W

Compute the Hamiltonian energy for a spin configuration.

Trait Implementations

impl<G: Clone, W: Clone> Clone for SpinGlass<G, W>

fn clone(&self) -> SpinGlass<G, W>

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<G: Debug, W: Debug> Debug for SpinGlass<G, W>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'de, G, W> Deserialize<'de> for SpinGlass<G, W>

where G: Deserialize<'de>, W: Deserialize<'de>,

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl<G, W> OptimizationProblem for SpinGlass<G, W>

where G: Graph + VariantParam, W: WeightElement + VariantParam + PartialOrd + Num + Zero + Bounded + AddAssign + Mul<Output = W> + From<i32>,

type Value = <W as WeightElement>::Sum

The inner objective value type (e.g., i32, f64).

fn direction(&self) -> Direction

Whether to maximize or minimize the metric.

impl<G, W> Problem for SpinGlass<G, W>

where G: Graph + VariantParam, W: WeightElement + VariantParam + PartialOrd + Num + Zero + Bounded + AddAssign + Mul<Output = W> + From<i32>,

const NAME: &'static str = "SpinGlass"

Base name of this problem type (e.g., “MaximumIndependentSet”).

type Metric = SolutionSize<<W as WeightElement>::Sum>

The evaluation metric type.

fn dims(&self) -> Vec<usize>

Configuration space dimensions. Each entry is the cardinality of that variable.

fn evaluate(&self, config: &[usize]) -> SolutionSize<W::Sum>

Evaluate the problem on a configuration.

fn variant() -> Vec<(&'static str, &'static str)>

Returns variant attributes derived from type parameters.

fn num_variables(&self) -> usize

Number of variables (derived from dims).

impl ReduceTo<MaxCut<SimpleGraph, i32>> for SpinGlass<SimpleGraph, i32>

type Result = ReductionSGToMaxCut<i32>

The reduction result type.

fn reduce_to(&self) -> Self::Result

Reduce this problem to the target problem type.

impl ReduceTo<QUBO> for SpinGlass<SimpleGraph, f64>

type Result = ReductionSGToQUBO

The reduction result type.

fn reduce_to(&self) -> Self::Result

Reduce this problem to the target problem type.

impl ReduceTo<SpinGlass<SimpleGraph, f64>> for QUBO<f64>

type Result = ReductionQUBOToSG

The reduction result type.

fn reduce_to(&self) -> Self::Result

Reduce this problem to the target problem type.

impl ReduceTo<SpinGlass<SimpleGraph, f64>> for SpinGlass<SimpleGraph, i32>

type Result = ReductionAutoCast<SpinGlass<SimpleGraph, i32>, SpinGlass<SimpleGraph, f64>>

The reduction result type.

fn reduce_to(&self) -> Self::Result

Reduce this problem to the target problem type.

impl ReduceTo<SpinGlass<SimpleGraph, i32>> for CircuitSAT

type Result = ReductionCircuitToSG

The reduction result type.

fn reduce_to(&self) -> Self::Result

Reduce this problem to the target problem type.

impl ReduceTo<SpinGlass<SimpleGraph, i32>> for MaxCut<SimpleGraph, i32>

type Result = ReductionMaxCutToSG<i32>

The reduction result type.

fn reduce_to(&self) -> Self::Result

Reduce this problem to the target problem type.

impl<G, W> Serialize for SpinGlass<G, W>

where G: Serialize, W: Serialize,

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl DeclaredVariant for SpinGlass<SimpleGraph, f64>

impl DeclaredVariant for SpinGlass<SimpleGraph, i32>