Scalar resources

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Scalar capacity is a Rust const generic: Graph<const D: usize>, Solver<D>, and the labeling and enumeration engines carry the same dimension. The default is 2. Any usize count can be instantiated explicitly; there is no runtime dimension dispatch or heap-backed scalar fallback. Each scalar state, vertex window, arc consumption vector, and hot dominance cache uses a fixed array.

use baldes::{Graph, Controls, price};

let mut graph = Graph::<4>::new(3, 4)?;
for vertex in 0..3 {
    for resource in 0..4 {
        graph.set_bounds(vertex, resource, 0., 10.)?;
    }
}
let first = graph.add_arc(0, 1, -2.)?;
let second = graph.add_arc(1, 2, -3.)?;
graph.arc_mut(first)?.consumption = [1., 2., 1., 3.].into();
graph.arc_mut(second)?.consumption = [2., 1., 4., 2.].into();
let result = price(&graph, &Controls::default())?;
assert_eq!(result.columns[0].resources, vec![3., 3., 5., 5.]);
# Ok::<(), baldes::core::error::OrError>(())

The constructor's resource count is the active count, at most D. This keeps zero- and one-resource models usable with capacity 2. add_resource(kind) initializes another coordinate within the compiled capacity and rejects overflow. Type annotations can use the default (let graph: Graph = Graph::new(3, 2)?;); standalone constructors should select it explicitly with Graph::<2>::new. ScalarValues<T, D> and ResourceValues<D> support indexing, slices, and array conversion with .into(). Exported routes contain only the active coordinates.

Python and default Rust builds

With make config, edit Scalar resource dimensions; the saved key is CONFIG_RESOURCE_DIMENSIONS (default 2).

These APIs use one capacity fixed when the library is compiled. Set BALDES_RESOURCE_DIMENSIONS to change it; leaving it unset selects 2:

BALDES_RESOURCE_DIMENSIONS=5 cargo build --release --features clp
BALDES_RESOURCE_DIMENSIONS=5 maturin develop --features clp

Use baldes::DEFAULT_RESOURCE_DIMENSIONS in Rust or pybaldes.resource_dimensions in Python to inspect that capacity. Creating or registering more resources returns an error. Rebuilding is required to change the capacity; there is no finite menu of runtime specializations. Explicit Rust types such as Graph::<9> work independently of this setting.

Resource semantics

Every active coordinate participates in extension, dominance, forward/backward joins, route reconstruction, enumeration, branching, resource knapsack charges, conservative path domains, and exact incumbent checks.

A disposable resource accumulates nonnegative arc consumption and may wait to reach a lower bound. An equality resource accumulates signed consumption without waiting. Arc windows constrain the head state after extension. Initial values default to source lower bounds. Backward equality search requires fixed sink windows; price selects forward search when those are not fixed.

Bucket indexing uses at most two selected axes, independently of scalar capacity. A resource above index one can be the main axis through Graph::main_resource. Positive EngineControls::steps or Solver::bucket_steps select additional disposable axes; at most one joins the main axis. Unselected resources still participate in feasibility and dominance. More active resources can retain more nondominated labels and increase time and memory. Existing resource-kind, NG, budget, and certificate-eligibility restrictions still apply.