Exploit dual degeneracy to reduce the number of integer infeasibilities - #1685

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chris-maes wants to merge 141 commits into

NVIDIA:mainfrom

chris-maes:dual_degenerate

Commits on Jul 20, 2026

Fix bugs causing primal simplex to cycle. Enable primal simplex cleanup after dual simplex
chris-maes
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63d1ba4

Commits on Jul 21, 2026

Primal simplex pivots on dual degenerate problems to reduce integer infeasibility
chris-maes
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8b1e60b
First stab at using the feasibility pump on a reduced problem on the optimal face
chris-maes
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17b2725

Commits on Jul 24, 2026

Add check for fast pivot using slacks
chris-maes
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ff6f460
Merge remote-tracking branch 'origin/main' into dual_degenerate
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5e31f6c

Commits on Jul 27, 2026

Enable primal simplex. Solves 85/93 NETLIB LPs in under 1 minute
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900805a

Commits on Jul 28, 2026

Use primal simplex to remove a perturbation from dual simplex
chris-maes
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efc9fb0

Commits on Jul 29, 2026

Clean up logging of degenerate feasibility pump
chris-maes
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cf3d4d4
Add work estimates to primal simplex
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a7cfd19
Display work estimate and simplex iterations
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6dfebbf

Commits on Aug 4, 2026

Primal in crossover. Crossover tolerance mismatch fix. Pipe work estimates for root relaxation. Add initial perturbation parameter
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99d7ead

Commits on Aug 6, 2026

Merge remote-tracking branch 'cuopt-nvidia/main' into dual_degenerate
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adcb8c2
Address coderabbit review comments
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0cfc746
Address coderabbit review comments
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1c2c01a
Use tight tol for reduced costs zero check
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b2de00d
Try to clean up normalization
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a92825c
Remove AI slop
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31436ba
Style fixes
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ef75207
Fix work estimate bug in BFRT. And improve work estimates
chris-maes
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117b2b4

Commits on Aug 7, 2026

Harris ratio test; timers in primal; limit feasibility pump to do less work than root relaxation
chris-maes
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99207b2

Commits on Aug 8, 2026

Add reduced cost bounds table. Change objective in feasibility pump. Fix work limit in feasibility pump. Check for reduced cost violation before calling primal simplex. Check if we reduced number o…
chris-maes
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eb47c20

Commits on Aug 12, 2026

V3 of pump and pivots, better work estimates, also exploit primal degeneracy
chris-maes
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7641ad3

Commits on Aug 14, 2026

Devex pricing in primal; try to remove perturbations in dual
chris-maes
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39cb576

Commits on Aug 26, 2026

Commits on Aug 27, 2026

Have BFRT decide on bound flips
chris-maes
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36ca4d3

Commits on Aug 28, 2026

Improve BFRT work estimates
chris-maes
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75a1e97
Merge remote-tracking branch 'cuopt-nvidia/main' into dual_degenerate
chris-maes
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47e0848

Commits on Aug 29, 2026

Fix bug in not handling concurrent halt. Use zero_tol in step-length computation to try to remain dual feasible
chris-maes
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d983159

Commits on Sep 3, 2026

Style fixes
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bfcbb15
Prefer large pivots with Harris ratio buckets
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c3a0251
Add parameters to control degenerate pivots
chris-maes
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ef5ff66
Style fixes
chris-maes
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2e02e23

Commits on Sep 4, 2026

Snapshot slack columns for branch-and-bound workers
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0f95053

Commits on Sep 9, 2026

Restrict concurrent halt to root LP solves
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9acaebc
Preserve caller cancellation in node LP solves
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4da4349
Prefer large pivots with Harris ratio buckets
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8c93985

Commits on Sep 10, 2026

Remove tiny perturbations before retrying dual simplex
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553b1fc
Replaced cusparse wrappers with simple unique_ptrs and more RAII (#1342)

Bubullzz
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62638a7
Forward routing gRPC settings and map node name strings to ints (#1837)

tmckayus
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chris-maes
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74865d3
Set Papilo back to the main branch (#1694)

nguidotti
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chris-maes
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b43fae0
Adopt CUDA stream compatibility accessors (#1858)

bdice
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a0435e5
move server LPData transform into a standalone function (#1848)

tmckayus
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0f79f11
refactor: make to_optimization_problem a free function (#1802)

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34ac7fc
Extract LP create_data_model/create_solver into conversion.py (#1849)

tmckayus
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7e50453
Bump cuopt-java compile target from Java 11 to Java 17 (#1865)

ramakrishnap-nv
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chris-maes
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447aa22
extract routing server data creation routines into standalone module (#1850)

tmckayus
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chris-maes
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49f6d48
move server data compression handling into a standalone module (#1851)

tmckayus
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chris-maes
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e1238c3
fix(build): pin RAPIDS_BRANCH and shared-workflows to release/26.10 (#1870)

ramakrishnap-nv
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chris-maes
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70b0955
change Python grpc client so wait loop happens in Python (#1857)

tmckayus
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chris-maes
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4def469
add a smoke test to ensure server images start correctly (#1646)

tmckayus
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chris-maes
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8e3f264
refactor: keep the GPU warm-start path out of host-only translation units (#1803)

ramakrishnap-nv
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chris-maes
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52d6f08
extract result file support logic to be shared by proxy (#1869)

tmckayus
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chris-maes
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0a4415b
update variable type (#1783)

Iroy30
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chris-maes
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e6196f5
Move deprecated server modules into utils/deprecated. (#1874)

tmckayus
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cc21c5c
build: add the CUDA-free cuopt_client library (#1804)

ramakrishnap-nv
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chris-maes
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51f134d

Commits on Sep 11, 2026

Remove BFRT debug code
chris-maes
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deade2c
Remove tiny perturbations before retrying dual simplex
chris-maes
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60efd8b
Remove BFRT debug code
chris-maes
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4d9309c
Remove more debugging code
chris-maes
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f6f82f4
Remove unused unscaled max obj coeff
chris-maes
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3e04179
Remove unused unscaled max obj coeff
chris-maes
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2d948ec
Remove more debugging code
chris-maes
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ae8f903
Check time and concurrent halt in BFRT
chris-maes
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6deb6bb
Improve handling of primal simplex return status
chris-maes
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3311cdb
Remove primal clean up. We now do this inside dual simplex
chris-maes
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2920576
Check time and concurrent halt in BFRT
chris-maes
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52d8ccb
Improve handling of primal simplex return status
chris-maes
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ffaec11
Remove primal clean up. We now do this inside dual simplex
chris-maes
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2ede6e1
Fix comment
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74146b9
Fix comment
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53be7d4
Fix messages
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88e37c5
Fix messages
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8e0d79c
Remove unused variable
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7e9545a
Fix method. Add limit check at top of loop to avoid infinite loop
chris-maes
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b6a9318
Fix method. Add limit check at top of loop to avoid infinite loop
chris-maes
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61ddbf1
Refactor primal cleanup
chris-maes
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fa84590
Refactor primal cleanup
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f084344
Fix work estimate initialization
chris-maes
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cfcc5a4
Fix work estimate initialization
chris-maes
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dba71c3

Commits on Sep 12, 2026

Remove unused variable
chris-maes
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952cf05
Merge simplex improvements into dual_degenerate
chris-maes
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3883aa1
Merge cuopt-nvidia/main into simplex improvements
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f8237e6
Merge updated simplex base into dual_degenerate
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f020595
Format simplex improvements
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a7659d7
Merge shared formatting into dual_degenerate
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babeff2
Format MIP extensions
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c56bdae
Rename simplex parameters and default primal pricing to Devex
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8523f2b
Rename simplex parameters and default primal pricing to Devex
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9d10430
Merge shared simplex parameter updates
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a9003b0
Stop recursive sub-MIPs when branch-and-bound terminates
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bc99b1e
Use sparse reduced-cost updates for MIP strengthening
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8dd900b
Fix primal simplex pricing parameter test
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30cfc15
Merge branch 'primal_and_dual_simplex_improvements' into dual_degenerate
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0870da6

Commits on Sep 14, 2026

Validate dual simplex cutoffs with the original dual objective
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c642962

Commits on Sep 15, 2026

Commits on Sep 16, 2026

Avoid redundant reduced-cost product in cutoff validation
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9206716

Commits on Sep 18, 2026

Commits on Sep 22, 2026

Commits on Sep 23, 2026

Commits on Sep 24, 2026

Merge remote-tracking branch 'cuopt-nvidia/main' into dual_degenerate
chris-maes
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26b649f