Replace hardcoded canonical rule examples with ILPSolver calls by isPANN · Pull Request #775 · CodingThrust/problem-reductions

isPANN · 2026-03-26T03:25:04Z

Summary

Convert 46 ILP reduction rules from hardcoded SolutionPair to dynamic ILPSolver::new().solve() via new rule_example_via_ilp<S, V>() helper
Add z upper bound constraint in MinMaxMulticenter ILP formulation to prevent HiGHS stalling
Extract shared helper in example_db::specs, eliminating ~700 lines of boilerplate

Convention change

New ILP rule examples should use:

crate::example_db::specs::rule_example_via_ilp::<_, bool>(source)  // or i32

instead of hardcoding SolutionPair. See PR comment for details.

Test plan

cargo build --features example-db,ilp compiles cleanly
cargo test --features example-db,ilp — 3530 tests pass
rule_specs_solution_pairs_are_consistent validates all canonical examples

Closes #772

🤖 Generated with Claude Code

Convert 46 ILP reduction rules from hardcoded SolutionPair to dynamic ILPSolver::new().solve() calls, ensuring canonical examples actually verify the ILP solver can solve the reduction. Also adds a z upper bound constraint in MinMaxMulticenter ILP formulation to prevent HiGHS from stalling on unbounded [0, 2^31) domain. Closes #772 Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>

…plate Add `rule_example_via_ilp<S, V>()` to `example_db::specs` that performs reduce → ILP solve → extract → assemble in one call. This replaces the 8-line block that was copy-pasted across 60 ILP rule files, and also eliminates the double `reduce_to()` call (once explicit, once inside `rule_example_with_witness`). Also fixes stale docstring on `build_example_db()` which incorrectly claimed no solver is called. Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>

isPANN · 2026-03-26T03:26:15Z

Canonical rule example convention change

After this PR, the standard pattern for canonical_rule_example_specs() in *_ilp.rs files is:

#[cfg(feature = "example-db")]
pub(crate) fn canonical_rule_example_specs() -> Vec<crate::example_db::specs::RuleExampleSpec> {
    vec![crate::example_db::specs::RuleExampleSpec {
        id: "<source>_to_ilp",
        build: || {
            let source = /* construct instance */;
            crate::example_db::specs::rule_example_via_ilp::<_, bool>(source)  // or i32
        },
    }]
}

What changed:

rule_example_via_ilp<S, V>(source) replaces the old pattern of hardcoding SolutionPair { source_config: vec![...], target_config: vec![...] }
Internally it does: reduce_to() → ILPSolver::new().solve() → extract_solution() → assemble — in one call, with no double reduction
The use crate::export::SolutionPair import is no longer needed for ILP rules
rule_example_with_witness() still exists for non-ILP target rules that need a manually specified solution pair

For new ILP rules: just use rule_example_via_ilp. If the ILP solver hangs, it means the formulation needs tighter variable bounds (see minmaxmulticenter_ilp.rs for an example of adding a z upper bound).

codecov · 2026-03-26T03:28:42Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.79%. Comparing base (093c595) to head (49fc30f).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #775      +/-   ##
==========================================
- Coverage   97.80%   97.79%   -0.01%     
==========================================
  Files         580      580              
  Lines       65742    65250     -492     
==========================================
- Hits        64297    63811     -486     
+ Misses       1445     1439       -6

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Copilot

Pull request overview

This PR updates the example database infrastructure so canonical ILP reduction rule examples are computed dynamically by running the ILP solver (instead of relying on hardcoded SolutionPair witnesses), and it adds an explicit upper bound constraint in the MinMaxMulticenter→ILP formulation to improve HiGHS performance.

Changes:

Introduce rule_example_via_ilp<S, V>() helper to reduce→solve→extract and assemble canonical ILP rule examples in a single pass.
Replace hardcoded canonical SolutionPair witnesses across many ILP rule example specs with calls to rule_example_via_ilp.
Add a z <= z_upper constraint to MinMaxMulticenter→ILP and update related unit tests.

Reviewed changes

Copilot reviewed 64 out of 64 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
src/example_db/specs.rs	Adds `rule_example_via_ilp` helper for dynamic ILP-based canonical rule examples.
src/example_db/mod.rs	Updates docs to reflect ILP examples are solved at build time (feature-gated).
src/rules/minmaxmulticenter_ilp.rs	Adds `z` upper-bound constraint and switches canonical example to `rule_example_via_ilp`.
src/unit_tests/rules/minmaxmulticenter_ilp.rs	Updates constraint-count expectation to include the new `z` bound.
src/unit_tests/example_db.rs	Relaxes IntegralFlowBundles→ILP example assertions (now solver-produced).
src/rules/undirectedflowlowerbounds_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/travelingsalesman_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/timetabledesign_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/sumofsquarespartition_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/subgraphisomorphism_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/steinertreeingraphs_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/steinertree_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/stackercrane_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/shortestweightconstrainedpath_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/sequencingwithreleasetimesanddeadlines_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/sequencingtominimizeweightedtardiness_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/sequencingtominimizeweightedcompletiontime_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/sequencingtominimizemaximumcumulativecost_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/schedulingwithindividualdeadlines_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/ruralpostman_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/resourceconstrainedscheduling_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/rectilinearpicturecompression_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/qubo_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/quadraticassignment_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/precedenceconstrainedscheduling_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/pathconstrainednetworkflow_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/partitionintotriangles_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/partitionintopathsoflength2_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/partiallyorderedknapsack_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/optimallineararrangement_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/naesatisfiability_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/multiprocessorscheduling_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/multiplecopyfileallocation_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/mixedchinesepostman_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/minimumtardinesssequencing_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/minimumsummulticenter_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/minimumsetcovering_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/minimummultiwaycut_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/minimumhittingset_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/minimumfeedbackvertexset_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/minimumfeedbackarcset_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/minimumdominatingset_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/maximumsetpacking_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/maximummatching_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/maximumclique_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/maximalis_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/longestpath_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/longestcommonsubsequence_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/longestcircuit_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/lengthboundeddisjointpaths_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/integralflowwithmultipliers_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/integralflowhomologousarcs_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/integralflowbundles_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/hamiltonianpath_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/flowshopscheduling_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/factoring_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/disjointconnectingpaths_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/directedtwocommodityintegralflow_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/consistencyofdatabasefrequencytables_ilp.rs	Uses `rule_example_via_ilp` for canonical example; adjusts dead-code gating on encoder helper.
src/rules/consecutiveblockminimization_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/capacityassignment_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/bottlenecktravelingsalesman_ilp.rs	Switches canonical example to `rule_example_via_ilp`.
src/rules/bmf_ilp.rs	Switches canonical example to `rule_example_via_ilp`.

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Copilot · 2026-03-26T08:26:18Z

src/rules/mixedchinesepostman_ilp.rs

    use crate::rules::ReduceTo as _;
    use crate::topology::MixedGraph;


The use crate::rules::ReduceTo as _; import is no longer needed here (the example now uses rule_example_via_ilp) and will be unused under --features example-db. Please remove it to avoid warnings.

Copilot · 2026-03-26T08:26:18Z

src/rules/ruralpostman_ilp.rs

 #[cfg(feature = "example-db")]
 pub(crate) fn canonical_rule_example_specs() -> Vec<crate::example_db::specs::RuleExampleSpec> {
-    use crate::export::SolutionPair;
    use crate::rules::ReduceTo as _;


use crate::rules::ReduceTo as _; is unused now that the canonical example calls rule_example_via_ilp and no longer calls reduce_to() directly. Please drop the import to avoid warnings when building the example DB.

Copilot · 2026-03-26T08:26:18Z

src/rules/steinertreeingraphs_ilp.rs

    use crate::rules::ReduceTo as _;



use crate::rules::ReduceTo as _; is unused in this example-spec function after moving to rule_example_via_ilp. Please remove it to avoid unused-import warnings under --features example-db.

Copilot · 2026-03-26T08:26:19Z

src/unit_tests/example_db.rs

+    assert!(!example.solutions[0].source_config.is_empty());
+    assert!(!example.solutions[0].target_config.is_empty());


These assertions are very weak now: a non-empty config could still have the wrong length (which would make it invalid for the source problem / ILP). Consider asserting source_config.len() equals the number of arcs in the exported graph.arcs (for IntegralFlowBundles) and target_config.len() equals target.instance["num_vars"], which keeps the test solver-agnostic while still catching regressions in solution extraction/serialization.

Copilot · 2026-03-26T08:26:19Z

src/rules/stackercrane_ilp.rs

 #[cfg(feature = "example-db")]
 pub(crate) fn canonical_rule_example_specs() -> Vec<crate::example_db::specs::RuleExampleSpec> {
-    use crate::export::SolutionPair;
    use crate::rules::ReduceTo as _;


use crate::rules::ReduceTo as _; is no longer needed here (the example now delegates to rule_example_via_ilp), so this import becomes unused when example-db is enabled. Please remove it to avoid warning noise in cargo test --features "example-db ilp-highs".

Copilot · 2026-03-26T08:26:19Z

src/rules/disjointconnectingpaths_ilp.rs

    use crate::rules::ReduceTo as _;



use crate::rules::ReduceTo as _; appears unused now that this canonical example uses rule_example_via_ilp instead of calling reduce_to() directly. Removing it will avoid an unused-import warning under --features example-db.

Suggested change

use crate::rules::ReduceTo as _;

Copilot · 2026-03-26T08:26:19Z

src/rules/lengthboundeddisjointpaths_ilp.rs

    use crate::rules::ReduceTo as _;



use crate::rules::ReduceTo as _; is unused in this function after switching the example to rule_example_via_ilp. Please remove it to keep example-db builds warning-free.

Suggested change

use crate::rules::ReduceTo as _;

zazabap · 2026-03-26T09:34:09Z

Agentic Review Report

Structural Check

#	Check	Status
1	New helper `rule_example_via_ilp` correctly implemented	PASS
2	Feature gate `#[cfg(feature = "ilp-solver")]` on helper	PASS
3	Conversion pattern consistent across files	PASS
4	No leftover hardcoded configs in converted files	PASS
5	Tests pass (`cargo test`)	PASS
6	`cargo test --features "example-db ilp-highs"`	PASS (28 tests)
7	minmaxmulticenter_ilp z-bound addition is sound	PASS
8	minmaxmulticenter_ilp test updated for new constraint count	PASS
9	`cargo fmt --check`	FAIL — ~32 files have 8-space indentation instead of 4 in `canonical_rule_example_specs()` body

Issue 1 (Medium): Formatting — ~32 files fail cargo fmt --check
The vec![...] expression inside canonical_rule_example_specs() is indented with 8 spaces instead of 4 across ~32 files. Example: src/rules/maximumclique_ilp.rs:83. Must be fixed before merge.

Issue 2 (Medium): Incorrect overhead expression in src/rules/minmaxmulticenter_ilp.rs:119
The overhead num_constraints = "2 * num_vertices^2 + 4 * num_vertices + 2" should be "2 * num_vertices^2 + 3 * num_vertices + 2":

For n=3: 2(9) + 3(3) + 2 = 29 ✓ (matches test assertion on line 26)
Current formula: 2(9) + 4(3) + 2 = 32 ✗
The Vec::with_capacity hint on line 142 also uses the wrong formula (2*n*n + 4*n + 1).

Issue 3 (Low): 6 unused use crate::rules::ReduceTo as _; imports
Files: stackercrane_ilp.rs:203, mixedchinesepostman_ilp.rs:367, steinertreeingraphs_ilp.rs:129, disjointconnectingpaths_ilp.rs:173, ruralpostman_ilp.rs:218, lengthboundeddisjointpaths_ilp.rs:202. Copilot review comments confirmed.

Copilot comment on unit_tests/example_db.rs assertions: Not actionable — existing tests are comprehensive with round-trip validation and feasibility checks.

Quality Check

DRY — Improvement with incomplete coverage. The rule_example_via_ilp() helper eliminates duplicated ILP boilerplate from ~60 files. However, ~22 ILP rule files still use rule_example_with_witness with hardcoded configs (e.g., coloring_ilp.rs, knapsack_ilp.rs, binpacking_ilp.rs, kclique_ilp.rs). If these can't use the helper, rationale should be documented.

KISS — OK. The helper is 15 lines, clear, does one thing. No over-engineering.

HC/LC — OK. Helper lives in src/example_db/specs.rs alongside rule_example_with_witness, correct cohesion. Feature gating correct.

Issues:

(Medium) Weakened test assertion — src/unit_tests/example_db.rs:246-247: Previously asserted exact solution values, now only checks !is_empty(). Should at minimum verify solution vector lengths or evaluate against the source problem.
(Minor) MinMaxMulticenter reduction bugfix bundled — src/rules/minmaxmulticenter_ilp.rs:119-189 adds a z upper-bound constraint and changes the overhead formula. This is a behavioral fix to the reduction itself, not just DRY cleanup — should be noted.
(Minor) No dedicated unit test for rule_example_via_ilp — The helper is exercised indirectly through example_db, but a focused test would catch regressions faster.

Agentic Feature Tests

#	Command	Expected	Actual	Status
1	`make cli`	CLI builds	Built (7 compiler warnings — unused imports)	PASS
2	`cargo test`	All tests pass	80 passed, 0 failed, 5 ignored	PASS
3	`cargo test --features "example-db ilp-highs" -- example_db`	Example DB tests pass with ILP solver	28 passed, 0 failed	PASS
4	`cargo test --features "ilp-highs" -- minmaxmulticenter_ilp`	Minmax ILP tests pass	5 passed, 0 failed	PASS
5	`pred create --example MinimumCutIntoBoundedSets && pred solve`	End-to-end works	Created example, solved to `Min(6)`	PASS

7/7 feature tests pass. Minor: 7 compiler warnings (unused imports/variables).

Generated by review-pipeline

- Fix indentation in ~32 canonical_rule_example_specs functions (cargo fmt) - Fix incorrect overhead in minmaxmulticenter_ilp: num_constraints formula was 2n²+4n+2, correct is 2n²+3n+2 (matching actual constraint count: 1 cardinality + n assignment + n² link + n x-bounds + n² y-bounds + 1 z-bound + n minimax) - Fix Vec::with_capacity hint to match corrected formula - Remove 6 unused `use crate::rules::ReduceTo as _;` imports in files that switched to rule_example_via_ilp Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>

zazabap · 2026-03-26T09:49:22Z

All review findings addressed in 49fc30f:

Fixed indentation in ~32 files (cargo fmt)
Fixed incorrect overhead formula in minmaxmulticenter_ilp (2n²+4n+2 → 2n²+3n+2)
Removed 6 unused ReduceTo as _ imports

All CI checks pass.

zazabap

LGTM

zazabap

Reviewed: all review findings addressed, CI green, overhead formula corrected.

isPANN and others added 2 commits March 26, 2026 11:22

Merge branch 'main' into replace-hardcoded-ilp-examples-772-v2

07b9bde

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zazabap approved these changes Mar 26, 2026

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zazabap merged commit 0980d5a into main Mar 26, 2026
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zazabap deleted the replace-hardcoded-ilp-examples-772-v2 branch March 26, 2026 09:51

		use crate::rules::ReduceTo as _;
		use crate::topology::MixedGraph;

		assert!(!example.solutions[0].source_config.is_empty());
		assert!(!example.solutions[0].target_config.is_empty());

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isPANN commented Mar 26, 2026

Summary

Convention change

Test plan

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isPANN commented Mar 26, 2026

Canonical rule example convention change

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zazabap commented Mar 26, 2026

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codecov bot commented Mar 26, 2026 •

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