Fix #764: Delete GraphPartitioning, make it an alias of MaxCut (#776)

GraphPartitioning (minimum bisection) was a standalone model with its own
reduction rules to MaxCut, QUBO, and ILP. Since it is conceptually an alias
of MaxCut, remove the dedicated model, all three reduction rules, their
tests, CLI create handlers, paper entries, and register "GraphPartitioning"
as an alias on the MaxCut schema entry.

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: zazabap

docs/paper/reductions.typ

@@ -135,7 +135,6 @@ Registered problems: 50 types, 59 reductions, 69 variant nodes
   ExactCoverBy3Sets *                               X3C                 O(2^universe_size)
   Factoring *                                                        2  O(exp((m + n)^0.3333333333333333 * log(m + n)^0.6666666666666666))
   FlowShopScheduling *                                                  O(factorial(num_jobs))
-  GraphPartitioning/SimpleGraph *                                       O(2^num_vertices)
   HamiltonianPath/SimpleGraph *                                         O(1.657^num_vertices)
   ILP/bool *                                                         2  O(2^num_vars)
   ILP/i32                                                               O(num_vars^num_vars)

docs/src/cli.md

@@ -228,7 +228,6 @@ Flags by problem type:
   KClique                         --graph, --k
   MinimumMultiwayCut              --graph, --terminals, --edge-weights
   PartitionIntoTriangles          --graph
-  GraphPartitioning               --graph
   GeneralizedHex                  --graph, --source, --sink
   IntegralFlowWithMultipliers     --arcs, --capacities, --source, --sink, --multipliers, --requirement
   MinimumCutIntoBoundedSets       --graph, --edge-weights, --source, --sink, --size-bound

problemreductions-cli/src/cli.rs

@@ -13,8 +13,8 @@ use problemreductions::models::algebraic::{
 };
 use problemreductions::models::formula::Quantifier;
 use problemreductions::models::graph::{
-    DisjointConnectingPaths, GeneralizedHex, GraphPartitioning, HamiltonianCircuit,
-    HamiltonianPath, IntegralFlowBundles, LengthBoundedDisjointPaths, LongestCircuit, LongestPath,
+    DisjointConnectingPaths, GeneralizedHex, HamiltonianCircuit, HamiltonianPath,
+    IntegralFlowBundles, LengthBoundedDisjointPaths, LongestCircuit, LongestPath,
     MinimumCutIntoBoundedSets, MinimumDummyActivitiesPert, MinimumMultiwayCut, MixedChinesePostman,
     MultipleChoiceBranching, PathConstrainedNetworkFlow, RootedTreeArrangement, SteinerTree,
     SteinerTreeInGraphs, StrongConnectivityAugmentation,
@@ -537,7 +537,6 @@ fn example_for(canonical: &str, graph_type: Option<&str>) -> &'static str {
             _ => "--graph 0-1,1-2,2-3 --weights 1,1,1,1",
         },
         "KClique" => "--graph 0-1,0-2,1-3,2-3,2-4,3-4 --k 3",
-        "GraphPartitioning" => "--graph 0-1,1-2,2-3,0-2,1-3,0-3",
         "GeneralizedHex" => "--graph 0-1,0-2,0-3,1-4,2-4,3-4,4-5 --source 0 --sink 5",
         "IntegralFlowBundles" => {
             "--arcs \"0>1,0>2,1>3,2>3,1>2,2>1\" --bundles \"0,1;2,5;3,4\" --bundle-capacities 1,1,1 --source 0 --sink 3 --requirement 1 --num-vertices 4"
@@ -1135,19 +1134,6 @@ pub fn create(args: &CreateArgs, out: &OutputConfig) -> Result<()> {
             (data, resolved_variant.clone())
         }
 
-        // Graph partitioning (graph only, no weights)
-        "GraphPartitioning" => {
-            let (graph, _) = parse_graph(args).map_err(|e| {
-                anyhow::anyhow!(
-                    "{e}\n\nUsage: pred create GraphPartitioning --graph 0-1,1-2,2-3,0-2,1-3,0-3"
-                )
-            })?;
-            (
-                ser(GraphPartitioning::new(graph))?,
-                resolved_variant.clone(),
-            )
-        }
-
         // Generalized Hex (graph + source + sink)
         "GeneralizedHex" => {
             let usage =
@@ -5905,27 +5891,6 @@ fn create_random(
             )
         }
 
-        // GraphPartitioning (graph only, no weights; requires even vertex count)
-        "GraphPartitioning" => {
-            let num_vertices = if num_vertices % 2 != 0 {
-                eprintln!(
-                    "Warning: GraphPartitioning requires even vertex count; rounding {} up to {}",
-                    num_vertices,
-                    num_vertices + 1
-                );
-                num_vertices + 1
-            } else {
-                num_vertices
-            };
-            let edge_prob = args.edge_prob.unwrap_or(0.5);
-            if !(0.0..=1.0).contains(&edge_prob) {
-                bail!("--edge-prob must be between 0.0 and 1.0");
-            }
-            let graph = util::create_random_graph(num_vertices, edge_prob, args.seed);
-            let variant = variant_map(&[("graph", "SimpleGraph")]);
-            (ser(GraphPartitioning::new(graph))?, variant)
-        }
-
         // Hamiltonian Circuit (graph only, no weights)
         "HamiltonianCircuit" => {
             let edge_prob = args.edge_prob.unwrap_or(0.5);

problemreductions-cli/src/commands/create.rs

@@ -53,10 +53,10 @@ pub mod prelude {
         AcyclicPartition, BalancedCompleteBipartiteSubgraph, BicliqueCover,
         BiconnectivityAugmentation, BottleneckTravelingSalesman, BoundedComponentSpanningForest,
         DirectedTwoCommodityIntegralFlow, DisjointConnectingPaths, GeneralizedHex,
-        GraphPartitioning, HamiltonianCircuit, HamiltonianPath, IntegralFlowBundles,
-        IntegralFlowHomologousArcs, IntegralFlowWithMultipliers, IsomorphicSpanningTree, KClique,
-        KthBestSpanningTree, LengthBoundedDisjointPaths, LongestPath, MixedChinesePostman,
-        SpinGlass, SteinerTree, StrongConnectivityAugmentation, SubgraphIsomorphism,
+        HamiltonianCircuit, HamiltonianPath, IntegralFlowBundles, IntegralFlowHomologousArcs,
+        IntegralFlowWithMultipliers, IsomorphicSpanningTree, KClique, KthBestSpanningTree,
+        LengthBoundedDisjointPaths, LongestPath, MixedChinesePostman, SpinGlass, SteinerTree,
+        StrongConnectivityAugmentation, SubgraphIsomorphism,
     };
     pub use crate::models::graph::{
         KColoring, LongestCircuit, MaxCut, MaximalIS, MaximumClique, MaximumIndependentSet,

src/lib.rs

@@ -14,7 +14,7 @@ inventory::submit! {
     ProblemSchemaEntry {
         name: "MaxCut",
         display_name: "Max Cut",
-        aliases: &[],
+        aliases: &["GraphPartitioning"],
         dimensions: &[
             VariantDimension::new("graph", "SimpleGraph", &["SimpleGraph"]),
             VariantDimension::new("weight", "i32", &["i32"]),

src/models/graph/graph_partitioning.rs

@@ -9,7 +9,6 @@
 //! - [`MinimumFeedbackVertexSet`]: Minimum weight feedback vertex set in a directed graph
 //! - [`MaximumClique`]: Maximum weight clique
 //! - [`MaxCut`]: Maximum cut on weighted graphs
-//! - [`GraphPartitioning`]: Minimum bisection (balanced graph partitioning)
 //! - [`MinimumCutIntoBoundedSets`]: Minimum cut into bounded sets (Garey & Johnson ND17)
 //! - [`MinimumDummyActivitiesPert`]: Minimum dummy activities in activity-on-arc PERT networks
 //! - [`HamiltonianCircuit`]: Hamiltonian circuit (decision problem)
@@ -64,7 +63,6 @@ pub(crate) mod bounded_component_spanning_forest;
 pub(crate) mod directed_two_commodity_integral_flow;
 pub(crate) mod disjoint_connecting_paths;
 pub(crate) mod generalized_hex;
-pub(crate) mod graph_partitioning;
 pub(crate) mod hamiltonian_circuit;
 pub(crate) mod hamiltonian_path;
 pub(crate) mod integral_flow_bundles;
@@ -120,7 +118,6 @@ pub use bounded_component_spanning_forest::BoundedComponentSpanningForest;
 pub use directed_two_commodity_integral_flow::DirectedTwoCommodityIntegralFlow;
 pub use disjoint_connecting_paths::DisjointConnectingPaths;
 pub use generalized_hex::GeneralizedHex;
-pub use graph_partitioning::GraphPartitioning;
 pub use hamiltonian_circuit::HamiltonianCircuit;
 pub use hamiltonian_path::HamiltonianPath;
 pub use integral_flow_bundles::IntegralFlowBundles;
@@ -218,7 +215,6 @@ pub(crate) fn canonical_model_example_specs() -> Vec<crate::example_db::specs::M
     specs.extend(undirected_two_commodity_integral_flow::canonical_model_example_specs());
     specs.extend(strong_connectivity_augmentation::canonical_model_example_specs());
     specs.extend(rural_postman::canonical_model_example_specs());
-    specs.extend(graph_partitioning::canonical_model_example_specs());
     specs.extend(integral_flow_homologous_arcs::canonical_model_example_specs());
     specs.extend(minimum_feedback_arc_set::canonical_model_example_specs());
     specs.extend(optimal_linear_arrangement::canonical_model_example_specs());

src/models/graph/max_cut.rs

@@ -20,8 +20,8 @@ pub use formula::{
 pub use graph::{
     AcyclicPartition, BalancedCompleteBipartiteSubgraph, BicliqueCover, BiconnectivityAugmentation,
     BottleneckTravelingSalesman, BoundedComponentSpanningForest, DirectedTwoCommodityIntegralFlow,
-    DisjointConnectingPaths, GeneralizedHex, GraphPartitioning, HamiltonianCircuit,
-    HamiltonianPath, IntegralFlowBundles, IntegralFlowHomologousArcs, IntegralFlowWithMultipliers,
+    DisjointConnectingPaths, GeneralizedHex, HamiltonianCircuit, HamiltonianPath,
+    IntegralFlowBundles, IntegralFlowHomologousArcs, IntegralFlowWithMultipliers,
     IsomorphicSpanningTree, KClique, KColoring, KthBestSpanningTree, LengthBoundedDisjointPaths,
     LongestCircuit, LongestPath, MaxCut, MaximalIS, MaximumClique, MaximumIndependentSet,
     MaximumMatching, MinMaxMulticenter, MinimumCutIntoBoundedSets, MinimumDominatingSet,