[Cbc] How to turn off cuts and preprocessing?

Thu Jan 31 05:23:47 EST 2013

Ashutosh,

The main reason is because the code thought it worth preprocessing the 
problem after it had found a solution.  When it restarted search

Cbc0044I Reduced cost fixing - 37 rows, 49 columns - restarting search

cuts went back on.  However, even if this restart is switched off there 
was one cut generator left.

I have fixed so if you say cuts off then they stay off (hopefully).

John Forrest

On 31/01/13 07:29, Ashutosh Mahajan wrote:
> I want to turn off all cuts, all heuristics AND all preprocessing.
>
> If I try
> ./bin/cbc egout.mps -cuts off -heur off -preprocess off solve
>
> then the cuts are still generated. Surprisingly, if I turn on the preprocessing,
>
> /bin/cbc egout.mps -cuts off -heur off -preprocess on solve
> then cuts are disabled.
>
> I am using cbc stable 2.8. Here is the output. Am I doing something
> wrong? Thanks in advance. Cheers.
>
> Ashutosh.
>
>
> Welcome to the CBC MILP Solver
> Version: 2.8
> Build Date: Jan 30 2013
> Revision Number: 1862
>
> command line - ./bin/cbc /home/amahajan/instances/deluge/egout.mps
> -cuts off -heur off -preprocess off solve (default strategy 1)
> At line 15 NAME          EGOUT
> At line 16 ROWS
> At line 116 COLUMNS
> At line 315 RHS
> At line 316 BOUNDS
> At line 403 ENDATA
> Problem EGOUT has 98 rows, 141 columns and 282 elements
> Coin0008I EGOUT read with 0 errors
> Option for cutsOnOff changed from on to off
> Option for heuristicsOnOff changed from on to off
> Option for preprocess changed from sos to off
> Continuous objective value is 149.589 - 0.00 seconds
> Cbc0010I After 0 nodes, 1 on tree, 1e+50 best solution, best possible
> 367.08488 (0.00 seconds)
> Cbc0016I Integer solution of 624.70162 found by strong branching after
> 519 iterations and 12 nodes (0.01 seconds)
> Cbc0038I Full problem 98 rows 141 columns, reduced to 37 rows 49 columns
> Cbc0044I Reduced cost fixing - 37 rows, 49 columns - restarting search
> Cbc0012I Integer solution of 624.70162 found by Previous solution
> after 0 iterations and 0 nodes (0.00 seconds)
> Cbc0031I 12 added rows had average density of 5.1666667
> Cbc0013I At root node, 12 cuts changed objective from 511.58538 to
> 568.1007 in 4 passes
> Cbc0014I Cut generator 0 (Probing) - 21 row cuts average 2.0 elements,
> 0 column cuts (12 active)  in 0.000 seconds - new frequency is -100
> Cbc0014I Cut generator 1 (Gomory) - 13 row cuts average 10.7 elements,
> 0 column cuts (0 active)  in 0.000 seconds - new frequency is -100
> Cbc0014I Cut generator 2 (Knapsack) - 1 row cuts average 2.0 elements,
> 0 column cuts (0 active)  in 0.000 seconds - new frequency is -100
> Cbc0014I Cut generator 3 (Clique) - 0 row cuts average 0.0 elements, 0
> column cuts (0 active)  in 0.000 seconds - new frequency is -100
> Cbc0014I Cut generator 4 (FlowCover) - 6 row cuts average 3.8
> elements, 0 column cuts (0 active)  in 0.000 seconds - new frequency
> is -100
> Cbc0014I Cut generator 5 (MixedIntegerRounding2) - 11 row cuts average
> 5.7 elements, 0 column cuts (0 active)  in 0.000 seconds - new
> frequency is -100
> Cbc0004I Integer solution of 568.1007 found after 28 iterations and 0
> nodes (0.00 seconds)
> Cbc0001I Search completed - best objective 568.1006999999998, took 28
> iterations and 0 nodes (0.00 seconds)
> Cbc0035I Maximum depth 0, 0 variables fixed on reduced cost
> Cbc0038I Probing was tried 4 times and created 21 cuts of which 12
> were active after adding rounds of cuts (0.000 seconds)
> Cbc0038I Gomory was tried 4 times and created 13 cuts of which 0 were
> active after adding rounds of cuts (0.000 seconds)
> Cbc0038I Knapsack was tried 4 times and created 1 cuts of which 0 were
> active after adding rounds of cuts (0.000 seconds)
> Cbc0038I Clique was tried 4 times and created 0 cuts of which 0 were
> active after adding rounds of cuts (0.000 seconds)
> Cbc0038I FlowCover was tried 4 times and created 6 cuts of which 0
> were active after adding rounds of cuts (0.000 seconds)
> Cbc0038I MixedIntegerRounding2 was tried 4 times and created 11 cuts
> of which 0 were active after adding rounds of cuts (0.000 seconds)
> Cbc0012I Integer solution of 568.1007 found by Reduced search after
> 1491 iterations and 50 nodes (0.04 seconds)
> Cbc0001I Search completed - best objective 568.1007000000001, took
> 1491 iterations and 50 nodes (0.04 seconds)
> Cbc0032I Strong branching done 404 times (649 iterations), fathomed 18
> nodes and fixed 29 variables
> Cbc0035I Maximum depth 11, 8 variables fixed on reduced cost
> Cuts at root node changed objective from 347.637 to 367.085
>
> Result - Optimal solution found
>
> Objective value:                568.10070000
> Enumerated nodes:               50
> Total iterations:               1491
> Time (CPU seconds):             0.04
> Time (Wallclock seconds):       0.05
>
> Total time (CPU seconds):       0.04   (Wallclock seconds):       0.05
>
>
>
> Welcome to the CBC MILP Solver
> Version: 2.8
> Build Date: Jan 30 2013
> Revision Number: 1862
>
> command line - ./bin/cbc /home/amahajan/instances/deluge/egout.mps
> -cuts off -heur off -preprocess on solve (default strategy 1)
> At line 15 NAME          EGOUT
> At line 16 ROWS
> At line 116 COLUMNS
> At line 315 RHS
> At line 316 BOUNDS
> At line 403 ENDATA
> Problem EGOUT has 98 rows, 141 columns and 282 elements
> Coin0008I EGOUT read with 0 errors
> Option for cutsOnOff changed from on to off
> Option for heuristicsOnOff changed from on to off
> Option for preprocess changed from sos to on
> Continuous objective value is 149.589 - 0.00 seconds
> Cgl0003I 0 fixed, 0 tightened bounds, 14 strengthened rows, 0 substitutions
> Cgl0004I processed model has 36 rows, 48 columns (28 integer) and 97 elements
> Cbc0010I After 0 nodes, 1 on tree, 1e+50 best solution, best possible
> 511.61742 (0.00 seconds)
> Cbc0016I Integer solution of 583.453 found by strong branching after
> 19 iterations and 7 nodes (0.00 seconds)
> Cbc0016I Integer solution of 575.57088 found by strong branching after
> 19 iterations and 7 nodes (0.00 seconds)
> Cbc0016I Integer solution of 568.1007 found by strong branching after
> 30 iterations and 14 nodes (0.00 seconds)
> Cbc0001I Search completed - best objective 568.1007, took 122
> iterations and 46 nodes (0.02 seconds)
> Cbc0032I Strong branching done 276 times (393 iterations), fathomed 22
> nodes and fixed 15 variables
> Cbc0035I Maximum depth 6, 53 variables fixed on reduced cost
> Cuts at root node changed objective from 511.617 to 511.617
>
> Result - Optimal solution found
>
> Objective value:                568.10070000
> Enumerated nodes:               46
> Total iterations:               122
> Time (CPU seconds):             0.02
> Time (Wallclock seconds):       0.02
>
> Total time (CPU seconds):       0.02   (Wallclock seconds):       0.02
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