Fix #765: Upgrade 17 decision models to optimization (Group A + B) by isPANN · Pull Request #771 · CodingThrust/problem-reductions

isPANN · 2026-03-25T05:35:00Z

Summary

Upgrade all 17 decision models from Value = Or + threshold to true optimization (Value = Max<T> / Min<T>)
Rewrite 7 ILP rules from feasibility to optimization (add objective function, remove threshold constraint)
Redesign config space for 3 models with variable-length outputs (padding encoding)
Update CLI create commands, canonical examples, paper entries, and all tests

Group A — single-threshold models (12)

Model	Value	ILP	Config redesign
LongestCircuit	`Max<W::Sum>`
OptimalLinearArrangement	`Min<usize>`
RuralPostman	`Min<W::Sum>`
MixedChinesePostman	`Min<W::Sum>`
StackerCrane	`Min<i32>`
MinimumCardinalityKey	`Min<i64>`
SequencingToMinimizeMaximumCumulativeCost	`Min<i64>`
MultipleCopyFileAllocation	`Min<i64>`	✓
ExpectedRetrievalCost	`Min<f64>`	✓
SumOfSquaresPartition	`Min<i64>`	✓
LongestCommonSubsequence	`Max<usize>`	✓	✓ padding
ShortestCommonSupersequence	`Min<usize>`		✓ padding

Group B — constrained-optimization models (5)

Model	Keep (constraint)	Optimize	Value	ILP
MinimumCutIntoBoundedSets	`size_bound`	cut weight	`Min<W::Sum>`
ShortestWeightConstrainedPath	`weight_bound`	path length	`Min<N::Sum>`	✓
CapacityAssignment	`delay_budget`	cost	`Min<u128>`	✓
MinMaxMulticenter	`k` (centers)	max distance	`Min<W::Sum>`	✓ minimax
LengthBoundedDisjointPaths	`max_length`	# paths	`Max<usize>`

Test plan

make check (fmt + clippy + test) passes
cargo test --lib --features example-db — 3206 passed
cargo test -p problemreductions-cli — 17 passed
cargo test --test main (integration + doc tests) — all passed
cargo clippy --all-targets — 0 warnings

Closes #765

🤖 Generated with Claude Code

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

…Min<usize>) Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

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

…::Sum>) Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

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

…<i64>) Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

…to optimization (Min<i64>) Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

… (Min<i64>) + ILP rewrite Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

…<f64>) + ILP rewrite Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

…<i64>) + ILP rewrite Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

…Max<usize>) + ILP rewrite + config redesign Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

…n (Min<usize>) + config redesign Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

- Remove bound parameter from 8 model constructor calls in CLI create - Remove associated bound parsing/validation code and CLI tests - Fix SumOfSquaresPartition canonical example (optimal is 226, not 230) - Fix StackerCrane example-db test assertion (no longer has bound field) Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

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

…(Min<W::Sum>) Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

…ion (Min<N::Sum>) + ILP rewrite Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

…28>) + ILP rewrite Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

…Sum>) + minimax ILP rewrite Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

… (Max<usize>) + config redesign Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

…ptimization-765 # Conflicts: # docs/paper/reductions.typ

… merge - Convert 10 ILP rules from feasibility to optimization (remove bound, add objective) - Fix SCS ILP: add contiguous padding constraint, fix alphabet_size field - Mark OLA ILP<i32> tests as ignored (ILP solver too slow for integer variables) - Fix sequencing ILP test to use ILPSolver instead of brute-force on ILP<i32> Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

…nces - model_specs_are_optimal now tries brute-force first for instances with search space ≤ 2^20, avoiding HiGHS hangs on ILP<i32> reductions - Hardcode OLA and Sequencing ILP canonical example solutions (avoid calling ILPSolver at example-db build time for ILP<i32> targets) Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Root cause: ILP<i32> variables default to domain [0, 2^31], causing HiGHS to hang on even tiny instances. Two fixes: 1. ILP solver: derive tighter per-variable upper bounds from single-variable ≤ constraints before passing to HiGHS (covers x and p variables) 2. OLA ILP: add z_e ≤ n-1 bound (max position difference) 3. Sequencing ILP: add z ≤ Σ|costs| bound (max cumulative cost) Restores ILPSolver calls in canonical rule examples (removes hardcoded solutions) and reverts model_specs_are_optimal to ILP-first strategy. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

…lver test Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

codecov · 2026-03-25T09:03:30Z

Codecov Report

❌ Patch coverage is 99.25981% with 10 lines in your changes missing coverage. Please review.
✅ Project coverage is 97.81%. Comparing base (88fb8f7) to head (cd58bdf).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/models/graph/rural_postman.rs	75.00%	4 Missing ⚠️
...c/models/graph/shortest_weight_constrained_path.rs	88.23%	2 Missing ⚠️
src/models/graph/mixed_chinese_postman.rs	94.11%	1 Missing ⚠️
src/models/misc/longest_common_subsequence.rs	96.66%	1 Missing ⚠️
src/solvers/customized/solver.rs	95.65%	1 Missing ⚠️
...t_tests/rules/shortestweightconstrainedpath_ilp.rs	85.71%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #771      +/-   ##
==========================================
- Coverage   97.82%   97.81%   -0.01%     
==========================================
  Files         588      588              
  Lines       66422    66239     -183     
==========================================
- Hits        64976    64793     -183     
  Misses       1446     1446

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isPANN · 2026-03-25T09:11:38Z

Finding: ILP solver hangs due to unbounded variable domains

During this PR, we discovered that ILP<i32> reductions can cause HiGHS to hang indefinitely, even on tiny instances (e.g., 4 vertices / 23 variables).

Root cause

The ILP solver sets variable upper bounds from V::DIMS_PER_VAR:

v = v.max((V::DIMS_PER_VAR - 1) as f64);  // i32 → 2,147,483,647

For ILP<i32>, every variable gets domain [0, 2^31]. Even though constraints like x_{v,p} <= 1 or p_v <= n-1 logically bound variables to small ranges, HiGHS receives the full [0, 2^31] domain and its branch-and-bound becomes extremely slow.

This particularly affects auxiliary variables that lack explicit single-variable <= C constraints:

z variables in minimax formulations (OLA z_e, Sequencing z)
position/order variables only bounded via linking constraints (p_v = Σ p·x_{v,p})

Fix (3 parts)

ILP solver (src/solvers/ilp/solver.rs): Before passing to HiGHS, scan constraints for single-variable x_i <= C patterns and use the tighter bound instead of DIMS_PER_VAR
OLA ILP: Added z_e <= n-1 (max position difference)
Sequencing ILP: Added z <= Σ|costs| (max cumulative cost)

Impact

Before fix: model_specs_are_optimal hangs (OLA canonical example triggers OLA→ILP reduction path, HiGHS never returns).
After fix: all example-db tests pass in ~2 seconds.

Recommendation for future ILP rules

Always add explicit var <= upper_bound constraints for non-binary variables. This ensures HiGHS gets tight bounds regardless of DIMS_PER_VAR. See #772 for remaining hardcoded examples that should be converted.

…verage - Remove #[ignore] from OLA ILP tests (HiGHS is fast now with z bounds) - Add rural_postman tests: wrong config length, is_weighted, solver aggregate - Add SWCP test: weight bound exceeded - Covers codecov gaps in rural_postman, shortest_weight_constrained_path, and optimallineararrangement_ilp Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Copilot

Pull request overview

This PR upgrades a large set of models that were previously encoded as decision problems (Value = Or + threshold) into true optimization models (Value = Min/Max<T>), and updates the associated ILP reductions, CLI creation/help text, canonical examples, and tests so that solvers produce and validate optimal objective values.

Changes:

Convert 17 models from thresholded decision formulations to optimization (Min/Max) and update evaluate() to return objective values (Some(v) / None).
Rewrite multiple → ILP reductions from feasibility to optimization by removing bound constraints and adding objective functions (including minimax encodings where needed).
Update CLI help/tests/docs and unit/integration tests to reflect new constructors, config encodings (padding/slots), and optimization semantics.

Reviewed changes

Copilot reviewed 79 out of 79 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
tests/suites/integration.rs	Updates integration assertions to check `Value` presence for optimization models.
src/unit_tests/trait_consistency.rs	Updates constructors in trait consistency tests after removing threshold params.
src/unit_tests/solvers/customized/solver.rs	Adjusts customized-solver tests for new optimization semantics.
src/unit_tests/rules/sumofsquarespartition_ilp.rs	Updates SSP ILP tests to compare optimal values (BF vs ILP).
src/unit_tests/rules/stackercrane_ilp.rs	Switches round-trip helper to optimization variant; updates constructor.
src/unit_tests/rules/shortestweightconstrainedpath_ilp.rs	Updates SWCP ILP tests to optimization objective and `Min` values.
src/unit_tests/rules/shortestcommonsupersequence_ilp.rs	Updates SCS ILP tests for padding-based optimization objective.
src/unit_tests/rules/sequencingtominimizemaximumcumulativecost_ilp.rs	Updates STMMCC ILP tests to compare optimal objective values.
src/unit_tests/rules/ruralpostman_ilp.rs	Updates RPP ILP tests for optimization and adds BF-vs-ILP optimality check.
src/unit_tests/rules/optimallineararrangement_ilp.rs	Updates OLA ILP tests to optimization and adds BF-vs-ILP optimality check.
src/unit_tests/rules/multiplecopyfileallocation_ilp.rs	Updates MCFA ILP tests to optimization and removes budget constraint checks.
src/unit_tests/rules/mixedchinesepostman_ilp.rs	Updates MCPP ILP tests to optimization; adds BF-vs-ILP comparisons.
src/unit_tests/rules/minmaxmulticenter_ilp.rs	Updates MMC ILP tests to `ILP<i32>` minimax + objective variable `z`.
src/unit_tests/rules/minimumcutintoboundedsets_ilp.rs	Updates MinCutBS ILP tests to optimization round-trip helper and `Some` checks.
src/unit_tests/rules/longestcommonsubsequence_ilp.rs	Updates LCS ILP tests for padding encoding and BF-vs-ILP optimality checks.
src/unit_tests/rules/longestcircuit_ilp.rs	Updates LongestCircuit ILP tests to maximization objective and optimization helper.
src/unit_tests/rules/lengthboundeddisjointpaths_ilp.rs	Updates LBDP ILP tests to optimization round-trip helper (maximize #paths).
src/unit_tests/rules/expectedretrievalcost_ilp.rs	Updates ERC ILP tests to objective-based optimization and cost comparisons.
src/unit_tests/rules/capacityassignment_ilp.rs	Updates CA ILP tests to optimize cost subject to delay budget.
src/unit_tests/models/misc/sequencing_to_minimize_maximum_cumulative_cost.rs	Updates STMMCC model tests to `Min(Some(v))/Min(None)` semantics.
src/unit_tests/models/misc/expected_retrieval_cost.rs	Updates ERC model tests to return objective values (no threshold).
src/unit_tests/models/misc/capacity_assignment.rs	Updates CA model tests to `Min<u128>` objective and feasibility via delay budget.
src/unit_tests/models/graph/shortest_weight_constrained_path.rs	Updates SWCP model tests to `Min` objective and witness optimality assertions.
src/unit_tests/models/graph/multiple_copy_file_allocation.rs	Updates MCFA model tests to optimization objective and removes threshold logic.
src/unit_tests/models/graph/mixed_chinese_postman.rs	Updates MCPP model tests for optimization objective values.
src/unit_tests/models/graph/longest_circuit.rs	Updates LongestCircuit model tests for maximization objective values.
src/unit_tests/example_db.rs	Updates example-db assertions to reflect removed `bound` fields / new optimal values.
src/solvers/ilp/solver.rs	Tightens per-variable upper bounds using single-var `<=` constraints to improve ILP performance.
src/solvers/customized/solver.rs	Updates MinimumCardinalityKey customized backend to remove bound-based pruning.
src/rules/sumofsquarespartition_ilp.rs	Converts SSP ILP reduction from feasibility to minimization objective.
src/rules/stackercrane_ilp.rs	Converts StackerCrane ILP reduction from bound constraint to objective minimization.
src/rules/shortestweightconstrainedpath_ilp.rs	Converts SWCP ILP reduction to minimize length subject to weight constraint.
src/rules/shortestcommonsupersequence_ilp.rs	Implements padding + contiguous-padding constraints and objective for SCS minimization via maximizing padding.
src/rules/sequencingtominimizemaximumcumulativecost_ilp.rs	Converts STMMCC reduction to minimax ILP with explicit `z` objective variable.
src/rules/ruralpostman_ilp.rs	Converts RPP reduction from length-bound feasibility to objective minimization.
src/rules/optimallineararrangement_ilp.rs	Converts OLA reduction from bound feasibility to objective minimization.
src/rules/multiplecopyfileallocation_ilp.rs	Converts MCFA reduction to objective minimization and redefines Big-M for unreachable pairs.
src/rules/mixedchinesepostman_ilp.rs	Converts MCPP reduction from bound feasibility to objective minimization.
src/rules/minmaxmulticenter_ilp.rs	Converts MMC reduction to minimax `ILP<i32>` with binary bounds + `z` objective.
src/rules/minimumcutintoboundedsets_ilp.rs	Converts MinCutBS reduction to objective minimization (removes cut bound).
src/rules/longestcircuit_ilp.rs	Converts LongestCircuit ILP reduction to maximization objective (removes length threshold).
src/rules/lengthboundeddisjointpaths_ilp.rs	Redesigns LBDP ILP reduction to maximize number of active path slots with activation vars.
src/rules/expectedretrievalcost_ilp.rs	Converts ERC reduction from bound feasibility to objective minimization.
src/rules/capacityassignment_ilp.rs	Converts CA reduction to objective minimization (cost) subject to delay constraint.
src/models/set/minimum_cardinality_key.rs	Converts MinimumCardinalityKey to `Min<i64>` objective and removes bound from schema/struct.
src/models/misc/sum_of_squares_partition.rs	Converts SSP model to `Min<i64>` objective and removes bound field/serialization.
src/models/misc/stacker_crane.rs	Converts StackerCrane model to `Min<i32>` objective and removes bound.
src/models/misc/sequencing_to_minimize_maximum_cumulative_cost.rs	Converts STMMCC model to `Min<i64>` objective and removes bound.
src/models/misc/mod.rs	Updates misc model list entry for StackerCrane to reflect optimization semantics.
src/models/misc/longest_common_subsequence.rs	Converts LCS to padding-based fixed-length encoding and `Max<usize>` objective.
src/models/misc/expected_retrieval_cost.rs	Converts ERC to `Min<f64>` objective and removes bound.
src/models/misc/capacity_assignment.rs	Converts CA to `Min<u128>` objective and removes cost budget.
src/models/graph/optimal_linear_arrangement.rs	Converts OLA to `Min<usize>` objective and removes bound.
src/models/graph/multiple_copy_file_allocation.rs	Converts MCFA to `Min<i64>` objective and removes bound.
src/models/graph/mixed_chinese_postman.rs	Converts MCPP to `Min<W::Sum>` objective and removes bound.
src/models/graph/minimum_cut_into_bounded_sets.rs	Converts MinCutBS to `Min<W::Sum>` objective and removes cut bound.
src/models/graph/min_max_multicenter.rs	Converts MMC to `Min<W::Sum>` objective and removes bound.
src/models/graph/longest_circuit.rs	Converts LongestCircuit to `Max<W::Sum>` objective and removes bound.
problemreductions-cli/src/mcp/tests.rs	Updates MCP test payloads to reflect removed bound parameter(s).
problemreductions-cli/src/cli.rs	Updates CLI “flags by problem type” + args docs for removed parameters.
docs/src/cli.md	Updates docs output/examples for renamed fields and updated parameterization.

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Copilot · 2026-03-25T09:52:45Z

src/solvers/customized/solver.rs

+    // Search for any minimal key (the smallest one will be found first due to
+    // branch-and-bound ordering in the FD subset search)
    let result = fd_subset_search::search_fd_subset(
        n,
        &essential,


solve_minimum_cardinality_key currently searches for any minimal key (subset-minimal superkey) and returns the first one found. search_fd_subset does DFS that tries including each attribute first, so the first minimal key found is biased toward larger keys and is not guaranteed to be the minimum-cardinality key required by the optimization objective. Please change the search strategy to guarantee minimum size (e.g., iterative deepening by cardinality with pruning, or change the DFS order to explore smaller subsets first while maintaining minimality checks), and add an assertion in tests that the customized solver’s returned witness matches the brute-force optimum cardinality/value.

Copilot · 2026-03-25T09:52:45Z

problemreductions-cli/src/cli.rs

-  MinimumCutIntoBoundedSets       --graph, --edge-weights, --source, --sink, --size-bound, --cut-bound
+  MinimumCutIntoBoundedSets       --graph, --edge-weights, --source, --sink, --size-bound
  HamiltonianCircuit, HC          --graph
  LongestCircuit                  --graph, --edge-weights, --bound


The CLI help still lists LongestCircuit as requiring --bound, but the model (and create implementation) has been upgraded to optimization and no longer has a bound parameter. Update the flags-by-problem-type list accordingly so users aren’t instructed to pass an unused/invalid flag.

Suggested change

LongestCircuit --graph, --edge-weights, --bound

LongestCircuit --graph, --edge-weights

Copilot · 2026-03-25T09:52:46Z

problemreductions-cli/src/cli.rs

    #[arg(long)]
    pub required_edges: Option<String>,
-    /// Bound parameter (lower bound for LongestCircuit; upper or length bound for BoundedComponentSpanningForest, GroupingBySwapping, LengthBoundedDisjointPaths, LongestCommonSubsequence, MultipleCopyFileAllocation, MultipleChoiceBranching, OptimalLinearArrangement, RootedTreeArrangement, RuralPostman, ShortestCommonSupersequence, or StringToStringCorrection)
+    /// Bound parameter (lower bound for LongestCircuit; upper or length bound for BoundedComponentSpanningForest, GroupingBySwapping, LengthBoundedDisjointPaths, LongestCommonSubsequence, MultipleCopyFileAllocation, MultipleChoiceBranching, RootedTreeArrangement, RuralPostman, or StringToStringCorrection)


The --bound flag docstring still mentions models that no longer take a bound (e.g., LongestCircuit, LongestCommonSubsequence, MultipleCopyFileAllocation). This makes pred create help misleading after the optimization upgrade; please remove those models from this description (and consider deleting the flag entirely if nothing uses it anymore).

Suggested change

/// Bound parameter (lower bound for LongestCircuit; upper or length bound for BoundedComponentSpanningForest, GroupingBySwapping, LengthBoundedDisjointPaths, LongestCommonSubsequence, MultipleCopyFileAllocation, MultipleChoiceBranching, RootedTreeArrangement, RuralPostman, or StringToStringCorrection)

/// Bound parameter (upper or length bound for BoundedComponentSpanningForest, GroupingBySwapping, LengthBoundedDisjointPaths, MultipleChoiceBranching, RootedTreeArrangement, RuralPostman, or StringToStringCorrection)

Copilot · 2026-03-25T09:52:46Z

docs/src/cli.md

 pred create MaxCut --graph 0-1,1-2,2-0 -o maxcut.json
-pred create MinMaxMulticenter --graph 0-1,1-2,2-3 --weights 1,1,1,1 --edge-weights 1,1,1 --k 2 --bound 1 -o pcenter.json
+pred create MinMaxMulticenter --graph 0-1,1-2,2-3 --weights 1,1,1,1 --edge-weights 1,1,1 --k 2 -o pcenter.json
 pred create ShortestWeightConstrainedPath --graph 0-1,0-2,1-3,2-3,2-4,3-5,4-5,1-4 --edge-lengths 2,4,3,1,5,4,2,6 --edge-weights 5,1,2,3,2,3,1,1 --source-vertex 0 --target-vertex 5 --length-bound 10 --weight-bound 8 -o swcp.json


The SWCP example still uses --length-bound, but the CLI flags list above (and the model upgrade) removed that parameter. This example should be updated to remove --length-bound (and keep only --weight-bound) so it remains runnable.

Suggested change

pred create ShortestWeightConstrainedPath --graph 0-1,0-2,1-3,2-3,2-4,3-5,4-5,1-4 --edge-lengths 2,4,3,1,5,4,2,6 --edge-weights 5,1,2,3,2,3,1,1 --source-vertex 0 --target-vertex 5 --length-bound 10 --weight-bound 8 -o swcp.json

pred create ShortestWeightConstrainedPath --graph 0-1,0-2,1-3,2-3,2-4,3-5,4-5,1-4 --edge-lengths 2,4,3,1,5,4,2,6 --edge-weights 5,1,2,3,2,3,1,1 --source-vertex 0 --target-vertex 5 --weight-bound 8 -o swcp.json

Copilot · 2026-03-25T09:52:46Z

src/models/misc/longest_common_subsequence.rs

+    pub fn new(alphabet_size: usize, strings: Vec<Vec<usize>>) -> Self {
+        let max_length = strings.iter().map(|s| s.len()).min().unwrap_or(0);
+        assert!(
+            max_length >= 1 || strings.is_empty(),
+            "at least one string must be non-empty"
+        );


LongestCommonSubsequence::new computes max_length as the minimum string length, but then asserts that at least one string must be non-empty. This panics for valid instances where any input string is empty (the correct optimum is length 0), and also for the case where all strings are empty. Please allow max_length == 0 and handle it consistently (e.g., allow an empty config/dims, or special-case to a 0-length padded encoding) instead of panicking.

zazabap · 2026-03-25T10:58:08Z

Agentic Review Report

Structural Check

Structural Review: Generic (17 Model Upgrades + ILP Rule Rewrites)

Build Status

make test: PASS
make clippy: PASS

Blacklisted Files

PASS — none of the four auto-generated files appear in the diff.

Semantic Review — Models Sampled (6)

Model	evaluate()	dims()	Threshold removed	declare_variants!
OptimalLinearArrangement	OK — `Min(Some(cost))` for valid perms, `Min(None)` otherwise	OK — `vec![n; n]`	OK	OK
LongestCircuit	OK — `Max(Some(total_length))` for valid circuits	OK — `vec![2; num_edges]`	OK	OK
LongestCommonSubsequence	OK — padding validation correct	OK — `vec![alphabet_size+1; max_length]`	OK	OK
ShortestWeightConstrainedPath	OK — weight bound as constraint, length as objective	OK — `vec![2; num_edges]`	OK — `length_bound` removed, `weight_bound` kept	OK
MinMaxMulticenter	OK — multi-source Dijkstra for max distance	OK — `vec![2; num_vertices]`	OK — `bound` removed, `k` kept	OK
LengthBoundedDisjointPaths	OK — counts valid non-empty path slots	OK — `vec![2; max_paths * num_vertices]`	OK — `num_paths_required` removed, `max_length` kept	OK

Semantic Review — ILP Rules Sampled (4)

Rule	Objective	extract_solution	Overhead
OLA → ILP	OK — minimize `sum z_e`	OK	ISSUE — `num_constraints` under-counts by `num_edges` (missing `z_e <= n-1` upper bounds)
LongestCircuit → ILP	OK — maximize `sum l_e * y_e`	OK	ISSUE — `num_vars` over-counts by `4 * num_edges`; `num_constraints` over-counts by `num_vertices + 2 * num_edges` (n-1 vs n commodity-count mismatch)
LCS → ILP	OK — maximize non-padding positions	OK	OK
SWCP → ILP	OK — minimize total path length	OK	OK

Mathematical Correctness

OLA trace (n=4 path): bijection assignment + abs-value linearization correct.
SWCP trace (3-vertex path): arc formulation + MTZ subtour elimination correct.
LCS trace (3-symbol strings): subsequence matching + padding contiguity correct.

Issue Compliance (#765)

All 17 models correctly upgraded:

Group A (12): LongestCircuit ✓, OptimalLinearArrangement ✓, RuralPostman ✓, MixedChinesePostman ✓, StackerCrane ✓, MinimumCardinalityKey ✓, SequencingToMinimizeMaximumCumulativeCost ✓, MultipleCopyFileAllocation ✓, ExpectedRetrievalCost ✓, SumOfSquaresPartition ✓, LongestCommonSubsequence ✓, ShortestCommonSupersequence ✓
Group B (5): MinimumCutIntoBoundedSets ✓, ShortestWeightConstrainedPath ✓, CapacityAssignment ✓, MinMaxMulticenter ✓, LengthBoundedDisjointPaths ✓
All threshold fields removed, all constraint parameters retained.
All 7 existing ILP rules rewritten + 9 new ILP rules added.

Issues Found

OLA→ILP overhead num_constraints under-counts by num_edges (src/rules/optimallineararrangement_ilp.rs:52)
LongestCircuit→ILP overhead num_vars over-counts by 4 * num_edges (src/rules/longestcircuit_ilp.rs:45)
LongestCircuit→ILP overhead num_constraints over-counts by num_vertices + 2 * num_edges (src/rules/longestcircuit_ilp.rs:46)

Quality Check

Quality Review

Design Principles

DRY: ISSUE (minor) — Padding validation logic in LongestCommonSubsequence::evaluate (src/models/misc/longest_common_subsequence.rs:145-175) and ShortestCommonSupersequence::evaluate (src/models/misc/shortest_common_supersequence.rs:136-168) follows an identical 6-step pattern. Could extract a shared validate_padded_config helper.
KISS: OK — Model upgrades are clean. Padding encoding is straightforward. ILP solver's upper_bounds tightening for ILP<i32> is sensible.
HC/LC: OK — Each model is self-contained. ILP rule files cleanly separate reduction from model. No mixed concerns.

HCI (CLI changed)

Error messages: ISSUE (important) — Several CLI usage strings still reference --bound for models that no longer accept it:
- problemreductions-cli/src/cli.rs:236 — LongestCircuit help still shows --bound
- problemreductions-cli/src/cli.rs:283-285 — MixedChinesePostman, RuralPostman, StackerCrane help still shows --bound
- problemreductions-cli/src/commands/create.rs:579,649,652,655,1837,1844,1872,3817 — example strings still show --bound for these models
- Users following these examples will pass --bound that is silently ignored.
Discoverability: OK — Updated descriptions properly reflect optimization semantics.
Consistency: ISSUE (important) — Some models had --bound removed from help text (OLA, MinMaxMulticenter, SumOfSquaresPartition, CapacityAssignment) while others (LongestCircuit, MixedChinesePostman, RuralPostman, StackerCrane) were missed.
Least surprise: ISSUE — Silently-ignored --bound flags from stale usage examples.
Feedback: OK

Test Quality

LCS tests: Good coverage of padding validation, subsequence checking, brute-force optimality. Minor issue: test_lcs_bruteforce_finds_optimum uses weak assertion Max(Some(v)) if v >= 1 instead of assert_eq!(value, Max(Some(2))).
RuralPostman tests: Good coverage. Properly checks Min(Some(cost)).
MinMaxMulticenter ILP tests: Good closed-loop BF vs ILP comparison.
LCS ILP tests: Good closed-loop testing. Tests all-padding case.
CustomizedSolver tests: Changed to remove bound from MinimumCardinalityKey but does not verify optimality.

Issues

Critical (Must Fix)

CustomizedSolver for MinimumCardinalityKey may return suboptimal witnesses (src/solvers/customized/solver.rs:69-98). The DFS search_fd_subset tries "include attribute first" before "exclude", tending to find keys with MORE attributes. Since MinimumCardinalityKey now uses Min<i64> (optimization), the customized solver must return an optimal witness. The comment at line 80-81 ("the smallest one will be found first due to branch-and-bound ordering") appears incorrect — the search order favors larger keys.

Important (Should Fix)

Stale CLI usage strings and help text still reference --bound for LongestCircuit, MixedChinesePostman, RuralPostman, StackerCrane across cli.rs and create.rs.

Minor (Nice to Have)

DRY: Duplicated padding validation in LCS and SCS evaluate().
Weak assertion: LCS brute-force test should check exact optimal value Max(Some(2)) instead of >= 1.

Agentic Feature Tests

Test Environment

Build: succeeded (8 pre-existing warnings, none from this PR)

Results

Model	list	show	create	solve	reduce	path
LongestCircuit	PASS	PASS	PASS	PASS (Max(18))	PASS	PASS
OptimalLinearArrangement	PASS	PASS	PASS	PASS (Min(11))	PASS	FAIL*
MinimumCardinalityKey	PASS	PASS	PASS	PASS (Min(2))	N/A	N/A
ShortestCommonSupersequence	PASS	PASS	PASS	PASS (Min(3))	PASS	PASS
MinMaxMulticenter	PASS	PASS	PASS	PASS (Min(1))	N/A	FAIL*

* Pre-existing issue: pred path X ILP fails when reduction targets ILP/i32 because bare ILP resolves to default ILP/bool. Not a regression from this PR.

Details

All 5 tested models correctly display optimization value types (Max/Min instead of Or)
ILP and brute-force solvers return consistent results for all tested models
Example creation works for all tested models
No regressions found from this PR

Issues Found

#	Issue	Severity	Classification
1	`pred path <Name> ILP` fails for models reducing to `ILP/i32` (not `ILP/bool`)	minor	confirmed, pre-existing

Generated by review-pipeline

- Fix CustomizedSolver for MinimumCardinalityKey to guarantee minimum cardinality using iterative deepening by subset size, not just any minimal key (critical correctness fix for optimization upgrade) - Remove stale --bound references from CLI help and usage strings for LongestCircuit, MixedChinesePostman, RuralPostman, StackerCrane, LCS, SCS, MinimumCardinalityKey, MultipleCopyFileAllocation, and SequencingToMinimizeMaximumCumulativeCost - Remove stale --num-paths-required from LengthBoundedDisjointPaths help - Remove stale --k from MinimumCardinalityKey help - Remove --length-bound from SWCP example in docs/src/cli.md - Fix OLA->ILP overhead num_constraints (add num_edges for z_e bounds) - Fix LongestCircuit->ILP overhead (n-1 commodities, not n) - Allow LCS max_length == 0 for empty input strings instead of panicking - Strengthen LCS brute-force test assertion to check exact optimal value - Add optimality assertions to CustomizedSolver MCK tests - Update cli_tests to reflect removed --bound flags Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

zazabap · 2026-03-25T11:59:26Z

Fix Summary (`cd58bdf`)

Addresses all review comments and agentic review findings from the previous round.

Review Comments Addressed

#	Comment	Fix
1	CustomizedSolver for MinimumCardinalityKey returns suboptimal witnesses (`src/solvers/customized/solver.rs:84`) — DFS search order biased toward larger keys	Rewrote `solve_minimum_cardinality_key` to use iterative deepening by cardinality. The search now tries the smallest possible key size first and increments until a minimal key is found, guaranteeing the returned witness has minimum cardinality. Added two optimality tests comparing against brute-force.
2	CLI help lists `--bound` for LongestCircuit (`cli.rs:236`)	Removed `--bound` from LongestCircuit help entry
3	`--bound` docstring lists removed models (`cli.rs:556`)	Updated docstring to only list models that still use `--bound` (BoundedComponentSpanningForest, GroupingBySwapping, LengthBoundedDisjointPaths, MultipleChoiceBranching, RootedTreeArrangement, StringToStringCorrection)
4	SWCP example uses removed `--length-bound` (`docs/src/cli.md:357`)	Removed `--length-bound 10` from the example
5	LCS panics on `max_length == 0` (`src/models/misc/longest_common_subsequence.rs:64`)	Removed the `max_length >= 1` assertion. Empty strings now produce `max_length = 0` with an empty config space, and `evaluate(&[])` returns `Max(Some(0))`. Added two tests for empty-string edge cases.

Agentic Review Findings Addressed

#	Finding	Fix
1	OLA→ILP overhead `num_constraints` under-counts by `num_edges` — missing `z_e <= n-1` upper bounds	Changed `2 * num_edges` → `3 * num_edges` in overhead expression (`src/rules/optimallineararrangement_ilp.rs:52`)
2	LongestCircuit→ILP overhead `num_vars` over-counts — flow uses `n-1` commodities, not `n`	Changed `3 * num_edges + num_vertices + 2 * num_edges * num_vertices` → `num_edges + num_vertices + 2 * num_edges * (num_vertices - 1)`
3	LongestCircuit→ILP overhead `num_constraints` over-counts — same n-1 vs n mismatch	Changed `num_vertices + 1 + num_vertices^2 + 2 * num_edges * num_vertices` → `1 + num_vertices^2 + 2 * num_edges * (num_vertices - 1)`
4	Stale `--bound` in CLI help/usage for 8+ models	Removed `--bound` from help text and `example_for` strings for: LongestCircuit, MixedChinesePostman, RuralPostman, StackerCrane, LCS, SCS, MinimumCardinalityKey (`--k`), MultipleCopyFileAllocation, SequencingToMinimizeMaximumCumulativeCost. Also removed stale `--num-paths-required` from LengthBoundedDisjointPaths.
5	Weak LCS test assertion — `assert!(matches!(value, Max(Some(v)) if v >= 1))`	Strengthened to `assert_eq!(value, Max(Some(2)))`
6	`pred path X ILP` fails for ILP/i32 targets	Pre-existing issue, not a regression from this PR — no fix needed

Not Addressed (deferred)

#	Finding	Reason
1	DRY: Duplicated padding validation in LCS/SCS `evaluate()`	Minor quality issue. Only two instances, logic is straightforward. Can be extracted in a follow-up if desired.

Verification

make check (fmt + clippy + test): ✅ all pass
Updated cli_tests.rs to reflect removed --bound flags (StackerCrane, SequencingToMinMCC)

zazabap

LGTM

zazabap

Reviewed: all review comments addressed, make check passes, fixes verified.

isPANN and others added 19 commits March 25, 2026 12:26

Upgrade LongestCircuit from decision (Or) to optimization (Max<W::Sum>)

3c851b2

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

Upgrade OptimalLinearArrangement from decision (Or) to optimization (…

1dc2e8b

…Min<usize>) Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Upgrade RuralPostman from decision (Or) to optimization (Min<W::Sum>)

47b5d8f

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

Upgrade MixedChinesePostman from decision (Or) to optimization (Min<W…

3029569

…::Sum>) Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Upgrade StackerCrane from decision (Or) to optimization (Min<i32>)

675bcf4

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

Upgrade MinimumCardinalityKey from decision (Or) to optimization (Min…

8793ce4

…<i64>) Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Upgrade SequencingToMinimizeMaximumCumulativeCost from decision (Or) …

3c3e49e

…to optimization (Min<i64>) Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Upgrade MultipleCopyFileAllocation from decision (Or) to optimization…

2f46676

… (Min<i64>) + ILP rewrite Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Upgrade ExpectedRetrievalCost from decision (Or) to optimization (Min…

85d0457

…<f64>) + ILP rewrite Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Upgrade SumOfSquaresPartition from decision (Or) to optimization (Min…

f7cd5d4

…<i64>) + ILP rewrite Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Upgrade LongestCommonSubsequence from decision (Or) to optimization (…

d8be6cd

…Max<usize>) + ILP rewrite + config redesign Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Upgrade ShortestCommonSupersequence from decision (Or) to optimizatio…

6174fd1

…n (Min<usize>) + config redesign Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

chore: rustfmt formatting fixes

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

Upgrade MinimumCutIntoBoundedSets from decision (Or) to optimization …

9345d9d

…(Min<W::Sum>) Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Upgrade ShortestWeightConstrainedPath from decision (Or) to optimizat…

52a5585

…ion (Min<N::Sum>) + ILP rewrite Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Upgrade CapacityAssignment from decision (Or) to optimization (Min<u1…

97abfbc

…28>) + ILP rewrite Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Upgrade MinMaxMulticenter from decision (Or) to optimization (Min<W::…

2d0a7b9

…Sum>) + minimax ILP rewrite Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Upgrade LengthBoundedDisjointPaths from decision (Or) to optimization…

0d0e253

… (Max<usize>) + config redesign Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

isPANN changed the title ~~Fix #765: Upgrade 12 Group A decision models to optimization~~ Fix #765: Upgrade 17 decision models to optimization (Group A + B) Mar 25, 2026

isPANN and others added 2 commits March 25, 2026 14:42

Merge remote-tracking branch 'origin/main' into upgrade-decision-to-o…

6013fa0

…ptimization-765 # Conflicts: # docs/paper/reductions.typ

zazabap self-requested a review March 25, 2026 08:29

isPANN and others added 3 commits March 25, 2026 16:42

Fix CLI test: remove --bound from MinimumCardinalityKey customized so…

62a00c7

…lver test Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

isPANN mentioned this pull request Mar 25, 2026

Replace hardcoded canonical rule examples with ILPSolver calls #772

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zazabap requested a review from Copilot March 25, 2026 09:47

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zazabap merged commit 66e9050 into main Mar 25, 2026
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Fix #765: Upgrade 17 decision models to optimization (Group A + B)#771

Fix #765: Upgrade 17 decision models to optimization (Group A + B)#771
zazabap merged 26 commits intomainfrom
upgrade-decision-to-optimization-765

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	LongestCircuit --graph, --edge-weights, --bound
	LongestCircuit --graph, --edge-weights

	/// Bound parameter (lower bound for LongestCircuit; upper or length bound for BoundedComponentSpanningForest, GroupingBySwapping, LengthBoundedDisjointPaths, LongestCommonSubsequence, MultipleCopyFileAllocation, MultipleChoiceBranching, RootedTreeArrangement, RuralPostman, or StringToStringCorrection)
	/// Bound parameter (upper or length bound for BoundedComponentSpanningForest, GroupingBySwapping, LengthBoundedDisjointPaths, MultipleChoiceBranching, RootedTreeArrangement, RuralPostman, or StringToStringCorrection)

	pred create ShortestWeightConstrainedPath --graph 0-1,0-2,1-3,2-3,2-4,3-5,4-5,1-4 --edge-lengths 2,4,3,1,5,4,2,6 --edge-weights 5,1,2,3,2,3,1,1 --source-vertex 0 --target-vertex 5 --length-bound 10 --weight-bound 8 -o swcp.json
	pred create ShortestWeightConstrainedPath --graph 0-1,0-2,1-3,2-3,2-4,3-5,4-5,1-4 --edge-lengths 2,4,3,1,5,4,2,6 --edge-weights 5,1,2,3,2,3,1,1 --source-vertex 0 --target-vertex 5 --weight-bound 8 -o swcp.json

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Summary

Group A — single-threshold models (12)

Group B — constrained-optimization models (5)

Test plan

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isPANN commented Mar 25, 2026

Finding: ILP solver hangs due to unbounded variable domains

Root cause

Fix (3 parts)

Impact

Recommendation for future ILP rules

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zazabap commented Mar 25, 2026

Agentic Review Report

Structural Check

Structural Review: Generic (17 Model Upgrades + ILP Rule Rewrites)

Build Status

Blacklisted Files

Semantic Review — Models Sampled (6)

Semantic Review — ILP Rules Sampled (4)

Mathematical Correctness

Issue Compliance (#765)

Issues Found

Quality Check

Quality Review

Design Principles

HCI (CLI changed)

Test Quality

Issues

Agentic Feature Tests

Test Environment

Results

Details

Issues Found

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zazabap commented Mar 25, 2026

Fix Summary (cd58bdf)

Review Comments Addressed

Agentic Review Findings Addressed

Not Addressed (deferred)

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isPANN commented Mar 25, 2026 •

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Fix Summary (`cd58bdf`)