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ELEAVE56 ERROR! Tried to put a fixed column variable into the basis
Building a certain MILP with indicator constraints produces the following the lines of error and causes the program to crash:
ELEAVE56 ERROR! Tried to put a fixed column variable into the basis. idx=72, lower=0, upper=0
ELEAVE56 ERROR! Tried to put a fixed column variable into the basis. idx=72, lower=0, upper=0
ELEAVE56 ERROR! Tried to put a fixed column variable into the basis. idx=79, lower=0, upper=0
The underlying issue was introduced between scip version 8.0.0 to 8.0.1 (scip 8.0.0 solves the problem correctly, scip 8.0.1 produces the error).
I use pyscipopt in python 3.7 to construct the problem. Both, version 4.2.0 and 4.0.0 work fine.
Here the "writeProblem" output (identical for scip 8.0.0 and 8.0.1):
\ SCIP STATISTICS
\ Problem name : model
\ Variables : 112 (26 binary, 0 integer, 0 implicit integer, 86 continuous)
\ Constraints : 123
Minimize
Obj: +1 x1 +0.6 x3 +1.1 x4 +0.75 x5 +1 x6 +0.8 x7 +1 x8 +1 x9 +1 x11 +1.5 x13 +1.2 x15
Subject to
c1: -1 x1 -0.6 x3 -1.1 x4 -0.75 x5 -1 x6 -0.8 x7 -1 x8 -1 x9 -1 x11 -1.5 x13 -1.2 x15 <= +0
c2: +1 x1 +0.6 x3 +1.1 x4 +0.75 x5 +1 x6 +0.8 x7 +1 x8 +1 x9 +1 x11 +1.5 x13 +1.2 x15 <= +4
c4: +1 x16 -1 x18 +1 x30 -1 x47 <= +0
c5: -1 x16 +0.4 x28 +1 x29 -1 x55 <= +0
c6: +1 x21 +1 x27 -1 x57 <= +0
c7: +1 x23 +1 x31 <= +0
c8: +1 x27 -1 x33 <= +0
c9: +4.5 x27 -1 x43 <= +0
c10: +1 x24 -100 x27 <= +0
c11: +1 x25 -100 x27 <= +0
c12: -100 x27 +1 x32 <= +0
c13: -100 x27 +1 x33 <= +0
c14: -100 x27 +1 x34 <= +0
c15: -1 x24 -100 x27 <= +0
c16: -100 x27 +1 x35 <= +0
c17: -100 x27 +1 x36 <= +0
c18: -1 x25 -100 x27 <= +0
c19: -100 x27 +1 x37 <= +0
c20: -100 x27 +1 x38 <= +0
c21: -10 x27 +1 x39 <= +0
c22: -100 x27 +1 x40 <= +0
c23: -100 x27 +1 x41 <= +0
c24: -100 x27 +1 x42 <= +0
c25: -0.1 x29 -1 x30 -4.5 x31 -1 x41 +100 x44 +100 x45 +100 x46 +100 x47 +100 x48 +100 x49 +100 x50 +100 x51
+100 x52 +100 x53 +100 x54 +10 x55 +100 x56 +100 x57 +100 x58 <= -1
c26: +1 x23 <= +0
c27: +1 x59 +9 x1 <= +9
c28: +1 x61 -4.9 x3 <= +0
c29: +1 x62 +10 x4 <= +10
c30: +1 x63 +10 x5 <= +10
c31: +1 x64 -10 x6 <= +0
c32: +1 x65 +9 x7 <= +9
c33: +1 x66 +9 x8 <= +9
c34: +1 x67 +5 x9 <= +5
c35: +1 x69 +9 x11 <= +9
c36: +1 x71 +9.8 x13 <= +9.8
c37: -1 x62 +4.9 x4 <= +4.9
c38: -1 x65 +10 x7 <= +10
c39: -1 x73 +5.5 x15 <= +5.5
c40: +1 x32 +1 x33 +1 x34 +1 x37 -1 x39 = +0
c41: -1 x25 -1 x32 +1 x36 +1 x38 = +0
c42: -1 x33 +1 x34 +1 x35 +1 x36 +1 x38 = +0
c43: +1 x24 -1 x34 +1 x35 = +0
c44: +1 x25 -1 x36 -1 x37 +1 x40 = +0
c45: -1 x35 -1 x36 -1 x38 +1 x41 = +0
c46: -1 x24 -1 x34 -1 x35 -1 x38 +1 x42 = +0
c47: +1 x26 -1 x36 +1 x43 = +0
c48: -1 x59 -1 x60 -1 x61 -1 x66 +1 x68 = +0
c49: +1 x59 -1 x64 -1 x65 -1 x67 = +0
c50: +1 x60 -1 x61 -1 x63 -1 x64 -1 x67 = +0
c51: +1 x61 +1 x62 -1 x63 = +0
c52: +1 x64 +1 x65 +1 x66 -1 x69 = +0
c53: +1 x63 +1 x64 +1 x67 -1 x70 = +0
c54: +1 x61 -1 x62 +1 x63 +1 x67 -1 x71 = +0
c55: +1 x64 -1 x72 +1 x73 = +0
constraint handler <xor> cannot print requested format
\ [xor] <XORcons>: xor(<x1>[B],<x74>[B]) = 1;
IndicatorCons: x74 = 1 -> +1 x16 -1 x17 -1 x46 <= +0
IndicatorCons: x3 = 1 -> +1 x16 +1 x18 -1 x19 -1 x22 -1 x48 <= +0
constraint handler <xor> cannot print requested format
\ [xor] <XORcons>: xor(<x5>[B],<x77>[B]) = 1;
IndicatorCons: x77 = 1 -> +1 x18 +1 x19 -1 x21 -1 x22 -1 x50 <= +0
IndicatorCons: x6 = 1 -> +1 x17 +1 x18 -1 x20 -1 x21 -1 x23 -1 x51 <= +0
constraint handler <xor> cannot print requested format
\ [xor] <XORcons>: xor(<x8>[B],<x80>[B]) = 1;
IndicatorCons: x80 = 1 -> +1 x16 -1 x20 -1 x53 <= +0
constraint handler <xor> cannot print requested format
\ [xor] <XORcons>: xor(<x9>[B],<x82>[B]) = 1;
IndicatorCons: x82 = 1 -> +1 x17 +1 x18 -1 x21 -1 x22 -1 x54 <= +0
constraint handler <xor> cannot print requested format
\ [xor] <XORcons>: xor(<x11>[B],<x84>[B]) = 1;
IndicatorCons: x84 = 1 -> +1 x20 -1 x28 -1 x56 <= +0
constraint handler <xor> cannot print requested format
\ [xor] <XORcons>: xor(<x13>[B],<x86>[B]) = 1;
IndicatorCons: x86 = 1 -> +1 x22 -1 x58 <= +0
constraint handler <xor> cannot print requested format
\ [xor] <XORcons>: xor(<x15>[B],<x88>[B]) = 1;
IndicatorCons: x88 = 1 -> -1 x23 <= +0
IndicatorCons: x1 = 1 -> +1 x32 <= +0
constraint handler <xor> cannot print requested format
\ [xor] <XORcons>: xor(<x3>[B],<x91>[B]) = 1;
IndicatorCons: x91 = 1 -> +1 x34 <= +0
IndicatorCons: x5 = 1 -> +1 x35 <= +0
constraint handler <xor> cannot print requested format
\ [xor] <XORcons>: xor(<x6>[B],<x94>[B]) = 1;
IndicatorCons: x94 = 1 -> +1 x36 <= +0
IndicatorCons: x8 = 1 -> +1 x37 <= +0
IndicatorCons: x9 = 1 -> +1 x38 <= +0
IndicatorCons: x11 = 1 -> +1 x40 <= +0
IndicatorCons: x13 = 1 -> +1 x42 <= +0
IndicatorCons: x15 = 1 -> +1 x73 <= +0
constraint handler <xor> cannot print requested format
\ [xor] <XORcons>: xor(<x4>[B],<x101>[B]) = 1;
IndicatorCons: x101 = 1 -> +1 x19 -1 x22 -1 x44 +1 x49 <= +0
IndicatorCons: x101 = 1 -> -1 x19 +1 x22 +1 x44 -1 x49 <= +0
constraint handler <xor> cannot print requested format
\ [xor] <XORcons>: xor(<x7>[B],<x104>[B]) = 1;
IndicatorCons: x104 = 1 -> -1 x17 +1 x20 -1 x45 +1 x52 <= +0
IndicatorCons: x104 = 1 -> +1 x17 -1 x20 +1 x45 -1 x52 <= +0
IndicatorCons: x4 = 1 -> +1 x24 <= +0
IndicatorCons: x4 = 1 -> -1 x24 <= +0
IndicatorCons: x7 = 1 -> +1 x25 <= +0
IndicatorCons: x7 = 1 -> -1 x25 <= +0
IndicatorCons: x15 = 1 -> +1 x26 <= +0
IndicatorCons: x15 = 1 -> -1 x26 <= +0
Bounds
0 <= x1 <= 1
0 <= x2 <= 0
0 <= x3 <= 1
0 <= x4 <= 1
0 <= x5 <= 1
0 <= x6 <= 1
0 <= x7 <= 1
0 <= x8 <= 1
0 <= x9 <= 1
0 <= x10 <= 0
0 <= x11 <= 1
0 <= x12 <= 0
0 <= x13 <= 1
0 <= x14 <= 0
0 <= x15 <= 1
0 <= x74 <= 1
0 <= x77 <= 1
0 <= x80 <= 1
0 <= x82 <= 1
0 <= x84 <= 1
0 <= x86 <= 1
0 <= x88 <= 1
0 <= x91 <= 1
0 <= x94 <= 1
0 <= x101 <= 1
0 <= x104 <= 1
x27 free
0 <= x59 <= 100
1 <= x60 <= 100
0 <= x61 <= 100
-100 <= x62 <= 100
0 <= x63 <= 100
0 <= x64 <= 100
-100 <= x65 <= 100
0 <= x66 <= 100
0 <= x67 <= 100
0 <= x68 <= 10
0 <= x69 <= 100
0.2 <= x70 <= 100
0 <= x71 <= 100
4.5 <= x72
x73 free
x16 free
x17 free
x18 free
x19 free
x20 free
x21 free
x22 free
x23 free
x24 free
x25 free
x26 free
Binaries
x1 x2 x3 x4 x5 x6 x7 x8 x9 x10 x11 x12 x13 x14 x15 x74 x77 x80 x82 x84 x86 x88 x91 x94 x101 x104
End
hi @VonAlphaBisZulu, I'm getting an error when trying to read in the file, could you write it as an MPS ?
Hi, you find the problem here attached. I don't know why, but the LP-file solves with both 8.0.0 and 8.0.1, while the MPS shows infeasible in both. I created both, LP and MPS at the same breakpoint with the function scip.writeProblem. And the error I described earlier doesn't show. Something doesn't fit.
I can reproduce my problem consistently. Not sure, how to share it correctly.
Can you model the xor constraints as linear constraints x+y=1? Or will you have more complicated xor constraints in the future?
Updated LP and MPS. Same situation as in previous comment, but I also get the lines mentioned in my first post. So, you should be able to reproduce the problem. In SCIP throwing these errors might be okay, but with pyscipopt this leads to a crash. Should this issue be moved to pyscipopt?
This is the output from SCIP 8.0.0
SCIP> read scip_issue_23.lp
read problem <scip_issue_23.lp>
============
original problem has 112 variables (26 bin, 0 int, 0 impl, 86 cont) and 121 constraints
SCIP> optimize
presolving:
(round 1, fast) 20 del vars, 16 del conss, 0 add conss, 18 chg bounds, 0 chg sides, 0 chg coeffs, 0 upgd conss, 40 impls, 0 clqs
(round 2, fast) 20 del vars, 16 del conss, 0 add conss, 18 chg bounds, 2 chg sides, 0 chg coeffs, 0 upgd conss, 42 impls, 0 clqs
(round 3, fast) 20 del vars, 16 del conss, 0 add conss, 19 chg bounds, 2 chg sides, 0 chg coeffs, 0 upgd conss, 42 impls, 0 clqs
(round 4, fast) 20 del vars, 16 del conss, 0 add conss, 20 chg bounds, 2 chg sides, 0 chg coeffs, 0 upgd conss, 42 impls, 0 clqs
(round 5, exhaustive) 20 del vars, 23 del conss, 0 add conss, 20 chg bounds, 9 chg sides, 0 chg coeffs, 0 upgd conss, 42 impls, 0 clqs
(round 6, exhaustive) 20 del vars, 23 del conss, 0 add conss, 20 chg bounds, 9 chg sides, 0 chg coeffs, 12 upgd conss, 42 impls, 0 clqs
(0.0s) probing cycle finished: starting next cycle
presolving (7 rounds: 7 fast, 3 medium, 3 exhaustive):
20 deleted vars, 23 deleted constraints, 0 added constraints, 20 tightened bounds, 0 added holes, 9 changed sides, 0 changed coefficients
88 implications, 1 cliques
presolved problem has 92 variables (11 bin, 0 int, 0 impl, 81 cont) and 98 constraints
12 constraints of type <varbound>
58 constraints of type <linear>
28 constraints of type <indicator>
transformed objective value is always integral (scale: 0.05)
Presolving Time: 0.00
time | node | left |LP iter|LP it/n|mem/heur|mdpt |vars |cons |rows |cuts |sepa|confs|strbr| dualbound | primalbound | gap | compl.
0.0s| 1 | 0 | 66 | - | 1220k | 0 | 92 | 100 | 70 | 0 | 0 | 2 | 0 | 0.000000e+00 | -- | Inf | unknown
0.0s| 1 | 2 | 120 | - | 1233k | 0 | 92 | 103 | 70 | 0 | 2 | 5 | 0 | 0.000000e+00 | -- | Inf | unknown
d 0.0s| 26 | 12 | 206 | 7.4 |fracdivi| 7 | 92 | 107 | 70 | 0 | 1 | 9 | 0 | 1.750000e+00 | 3.550000e+00 | 102.86%| 10.89%
* 0.0s| 47 | 0 | 262 | 5.2 | LP | 7 | 92 | 109 | 70 | 0 | 1 | 11 | 0 | 3.000000e+00 | 3.000000e+00 | 0.00%| 99.71%
SCIP Status : problem is solved [optimal solution found]
Solving Time (sec) : 0.00
Solving Nodes : 47
Primal Bound : +3.00000000000000e+00 (2 solutions)
Dual Bound : +3.00000000000000e+00
Gap : 0.00 %
This is the output from SCIP 8.0.1
SCIP> read scip_issue_23.lp
read problem <scip_issue_23.lp>
============
original problem has 112 variables (26 bin, 0 int, 0 impl, 86 cont) and 121 constraints
SCIP> optimize
presolving:
(round 1, fast) 20 del vars, 16 del conss, 0 add conss, 18 chg bounds, 0 chg sides, 0 chg coeffs, 0 upgd conss, 40 impls, 0 clqs
(round 2, fast) 20 del vars, 16 del conss, 0 add conss, 18 chg bounds, 2 chg sides, 0 chg coeffs, 0 upgd conss, 42 impls, 0 clqs
(round 3, fast) 20 del vars, 16 del conss, 0 add conss, 19 chg bounds, 2 chg sides, 0 chg coeffs, 0 upgd conss, 42 impls, 0 clqs
(round 4, fast) 20 del vars, 16 del conss, 0 add conss, 20 chg bounds, 2 chg sides, 0 chg coeffs, 0 upgd conss, 42 impls, 0 clqs
(round 5, exhaustive) 20 del vars, 23 del conss, 0 add conss, 20 chg bounds, 9 chg sides, 0 chg coeffs, 0 upgd conss, 42 impls, 0 clqs
(round 6, exhaustive) 20 del vars, 23 del conss, 0 add conss, 20 chg bounds, 9 chg sides, 0 chg coeffs, 12 upgd conss, 42 impls, 0 clqs
(0.0s) probing cycle finished: starting next cycle
(0.0s) symmetry computation skipped: there exist constraints that cannot be handled by symmetry methods.
presolving (7 rounds: 7 fast, 3 medium, 3 exhaustive):
20 deleted vars, 23 deleted constraints, 0 added constraints, 20 tightened bounds, 0 added holes, 9 changed sides, 0 changed coefficients
88 implications, 1 cliques
presolved problem has 92 variables (11 bin, 0 int, 0 impl, 81 cont) and 98 constraints
12 constraints of type <varbound>
58 constraints of type <linear>
28 constraints of type <indicator>
transformed objective value is always integral (scale: 0.05)
Presolving Time: 0.00
time | node | left |LP iter|LP it/n|mem/heur|mdpt |vars |cons |rows |cuts |sepa|confs|strbr| dualbound | primalbound | gap | compl.
0.0s| 1 | 0 | 66 | - | 3730k | 0 | 92 | 100 | 70 | 0 | 0 | 2 | 0 | 0.000000e+00 | -- | Inf | unknown
0.0s| 1 | 2 | 120 | - | 3737k | 0 | 92 | 103 | 70 | 0 | 2 | 5 | 0 | 0.000000e+00 | -- | Inf | unknown
ELEAVE56 ERROR! Tried to put a fixed column variable into the basis. idx=91, lower=-0, upper=0
d 0.0s| 26 | 12 | 207 | 7.4 |fracdivi| 7 | 92 | 107 | 70 | 0 | 1 | 9 | 0 | 1.750000e+00 | 3.550000e+00 | 102.86%| 10.89%
ELEAVE56 ERROR! Tried to put a fixed column variable into the basis. idx=91, lower=-0, upper=0
ELEAVE56 ERROR! Tried to put a fixed column variable into the basis. idx=42, lower=-0, upper=-0
ELEAVE56 ERROR! Tried to put a fixed column variable into the basis. idx=11, lower=-0, upper=-0
ELEAVE56 ERROR! Tried to put a fixed column variable into the basis. idx=11, lower=-0, upper=-0
* 0.0s| 47 | 0 | 279 | 5.6 | LP | 7 | 92 | 110 | 70 | 0 | 1 | 12 | 0 | 3.000000e+00 | 3.000000e+00 | 0.00%| 99.71%
SCIP Status : problem is solved [optimal solution found]
Solving Time (sec) : 0.00
Solving Nodes : 47
Primal Bound : +3.00000000000000e+00 (2 solutions)
Dual Bound : +3.00000000000000e+00
Gap : 0.00 %
I know my problem has some variables fixed to zero, and hopefully this is not what causes the error. I fix and resolve to generate alternative solutions. I understand that removing the variables would be better practice, but I still feel that this should not throw an error (and neither does SCIP 8.0.0, CPLEX or Gurobi).
Of course, this fixing and unfixing should work. So if this happens only through PySCIPOpt, can you provide a PySCIPOpt log? Does it abort after the first ELEAVE message?
Okay, this is the full output when I run my code in Python on verbosity level 4. On the last line, it just stalls out. Nothing happens after this point, and I have to interrupt. A CI pipeline of mine on Github, which uses PySCIPOpt, throws a sefault. Not sure after how much time.
I am uncertain if PySCIPOpt contributes anything to this output:
presolving:
(round 1, fast) 20 del vars, 17 del conss, 0 add conss, 18 chg bounds, 0 chg sides, 0 chg coeffs, 0 upgd conss, 40 impls, 0 clqs
(round 2, fast) 20 del vars, 17 del conss, 0 add conss, 18 chg bounds, 2 chg sides, 0 chg coeffs, 0 upgd conss, 42 impls, 0 clqs
(round 3, fast) 20 del vars, 17 del conss, 0 add conss, 20 chg bounds, 2 chg sides, 0 chg coeffs, 0 upgd conss, 42 impls, 0 clqs
(round 4, fast) 20 del vars, 18 del conss, 0 add conss, 20 chg bounds, 2 chg sides, 0 chg coeffs, 0 upgd conss, 42 impls, 0 clqs
(round 5, fast) 20 del vars, 18 del conss, 0 add conss, 21 chg bounds, 2 chg sides, 0 chg coeffs, 0 upgd conss, 42 impls, 0 clqs
(round 6, fast) 21 del vars, 19 del conss, 0 add conss, 21 chg bounds, 2 chg sides, 0 chg coeffs, 0 upgd conss, 42 impls, 0 clqs
(round 7, exhaustive) 21 del vars, 26 del conss, 0 add conss, 21 chg bounds, 9 chg sides, 0 chg coeffs, 0 upgd conss, 42 impls, 0 clqs
(round 8, exhaustive) 21 del vars, 26 del conss, 0 add conss, 21 chg bounds, 9 chg sides, 0 chg coeffs, 12 upgd conss, 42 impls, 0 clqs
(0.0s) probing cycle finished: starting next cycle
(0.0s) symmetry computation skipped: there exist constraints that cannot be handled by symmetry methods.
presolving (9 rounds: 9 fast, 3 medium, 3 exhaustive):
21 deleted vars, 26 deleted constraints, 0 added constraints, 21 tightened bounds, 0 added holes, 9 changed sides, 0 changed coefficients
88 implications, 1 cliques
presolved problem has 91 variables (11 bin, 0 int, 0 impl, 80 cont) and 97 constraints
12 constraints of type <varbound>
57 constraints of type <linear>
28 constraints of type <indicator>
transformed objective value is always integral (scale: 0.05)
Presolving Time: 0.00
time | node | left |LP iter|LP it/n|mem/heur|mdpt |vars |cons |rows |cuts |sepa|confs|strbr| dualbound | primalbound | gap | compl.
0.0s| 1 | 0 | 24 | - | 1144k | 0 | 91 | 97 | 41 | 0 | 0 | 0 | 0 | 0.000000e+00 | -- | Inf | unknown
0.0s| 1 | 0 | 31 | - | 1154k | 0 | 91 | 97 | 44 | 3 | 1 | 0 | 0 | 0.000000e+00 | -- | Inf | unknown
0.0s| 1 | 0 | 32 | - | 1169k | 0 | 91 | 97 | 45 | 4 | 2 | 0 | 0 | 0.000000e+00 | -- | Inf | unknown
0.0s| 1 | 0 | 33 | - | 1169k | 0 | 91 | 97 | 46 | 5 | 3 | 0 | 0 | 0.000000e+00 | -- | Inf | unknown
0.0s| 1 | 0 | 34 | - | 1169k | 0 | 91 | 97 | 47 | 6 | 4 | 0 | 0 | 0.000000e+00 | -- | Inf | unknown
0.0s| 1 | 2 | 37 | - | 1177k | 0 | 91 | 97 | 47 | 6 | 6 | 0 | 0 | 0.000000e+00 | -- | Inf | unknown
ELEAVE56 ERROR! Tried to put a fixed column variable into the basis. idx=72, lower=0, upper=0
d 0.0s| 33 | 12 | 126 | 3.3 |veclendi| 10 | 91 | 101 | 52 | 0 | 2 | 4 | 0 | 1.350000e+00 | 3.000000e+00 | 122.22%| 14.25%
ELEAVE56 ERROR! Tried to put a fixed column variable into the basis. idx=72, lower=0, upper=0
ELEAVE56 ERROR! Tried to put a fixed column variable into the basis. idx=79, lower=0, upper=0
SCIP Status : problem is solved [optimal solution found]
Solving Time (sec) : 0.00
Solving Nodes : 47
Primal Bound : +3.00000000000000e+00 (1 solutions)
Dual Bound : +3.00000000000000e+00
Gap : 0.00 %
[linear] <c124>: <x6>[B] (+1) +<x7>[B] (+1) +<x15>[B] (+1) <= 2;
;
violation: right hand side is violated by 1
all 1 solutions given by solution candidate storage are infeasible
presolving:
(round 1, fast) 20 del vars, 18 del conss, 0 add conss, 18 chg bounds, 0 chg sides, 0 chg coeffs, 0 upgd conss, 40 impls, 0 clqs
(round 2, fast) 20 del vars, 18 del conss, 0 add conss, 18 chg bounds, 2 chg sides, 0 chg coeffs, 0 upgd conss, 42 impls, 0 clqs
(round 3, fast) 20 del vars, 18 del conss, 0 add conss, 20 chg bounds, 2 chg sides, 0 chg coeffs, 0 upgd conss, 42 impls, 0 clqs
(round 4, fast) 20 del vars, 19 del conss, 0 add conss, 20 chg bounds, 2 chg sides, 0 chg coeffs, 0 upgd conss, 42 impls, 0 clqs
(round 5, fast) 20 del vars, 19 del conss, 0 add conss, 21 chg bounds, 2 chg sides, 0 chg coeffs, 0 upgd conss, 42 impls, 0 clqs
(round 6, fast) 21 del vars, 20 del conss, 0 add conss, 21 chg bounds, 2 chg sides, 0 chg coeffs, 0 upgd conss, 42 impls, 0 clqs
(round 7, exhaustive) 21 del vars, 27 del conss, 0 add conss, 21 chg bounds, 9 chg sides, 0 chg coeffs, 0 upgd conss, 42 impls, 0 clqs
(round 8, exhaustive) 21 del vars, 27 del conss, 0 add conss, 21 chg bounds, 9 chg sides, 0 chg coeffs, 13 upgd conss, 42 impls, 0 clqs
(0.0s) probing cycle finished: starting next cycle
(0.0s) symmetry computation skipped: there exist constraints that cannot be handled by symmetry methods.
presolving (9 rounds: 9 fast, 3 medium, 3 exhaustive):
21 deleted vars, 27 deleted constraints, 0 added constraints, 21 tightened bounds, 0 added holes, 9 changed sides, 0 changed coefficients
90 implications, 2 cliques
presolved problem has 91 variables (11 bin, 0 int, 0 impl, 80 cont) and 98 constraints
12 constraints of type <varbound>
57 constraints of type <linear>
1 constraints of type <logicor>
28 constraints of type <indicator>
transformed objective value is always integral (scale: 0.05)
Presolving Time: 0.00
time | node | left |LP iter|LP it/n|mem/heur|mdpt |vars |cons |rows |cuts |sepa|confs|strbr| dualbound | primalbound | gap | compl.
0.0s| 1 | 0 | 19 | - | 1416k | 0 | 91 | 98 | 42 | 0 | 0 | 0 | 0 | 0.000000e+00 | -- | Inf | unknown
0.0s| 1 | 0 | 26 | - | 1432k | 0 | 91 | 98 | 45 | 3 | 1 | 0 | 0 | 0.000000e+00 | -- | Inf | unknown
0.0s| 1 | 0 | 27 | - | 1432k | 0 | 91 | 98 | 46 | 4 | 2 | 0 | 0 | 0.000000e+00 | -- | Inf | unknown
0.0s| 1 | 0 | 28 | - | 1432k | 0 | 91 | 98 | 47 | 5 | 3 | 0 | 0 | 0.000000e+00 | -- | Inf | unknown
0.0s| 1 | 0 | 29 | - | 1432k | 0 | 91 | 98 | 48 | 6 | 4 | 0 | 0 | 0.000000e+00 | -- | Inf | unknown
0.0s| 1 | 2 | 32 | - | 1432k | 0 | 91 | 98 | 48 | 6 | 6 | 0 | 0 | 0.000000e+00 | -- | Inf | unknown
For completeness the output of SCIP 8.0.0
presolving:
(round 1, fast) 20 del vars, 17 del conss, 0 add conss, 18 chg bounds, 0 chg sides, 0 chg coeffs, 0 upgd conss, 40 impls, 0 clqs
(round 2, fast) 20 del vars, 17 del conss, 0 add conss, 18 chg bounds, 2 chg sides, 0 chg coeffs, 0 upgd conss, 42 impls, 0 clqs
(round 3, fast) 20 del vars, 17 del conss, 0 add conss, 20 chg bounds, 2 chg sides, 0 chg coeffs, 0 upgd conss, 42 impls, 0 clqs
(round 4, fast) 20 del vars, 18 del conss, 0 add conss, 20 chg bounds, 2 chg sides, 0 chg coeffs, 0 upgd conss, 42 impls, 0 clqs
(round 5, fast) 20 del vars, 18 del conss, 0 add conss, 21 chg bounds, 2 chg sides, 0 chg coeffs, 0 upgd conss, 42 impls, 0 clqs
(round 6, fast) 21 del vars, 19 del conss, 0 add conss, 21 chg bounds, 2 chg sides, 0 chg coeffs, 0 upgd conss, 42 impls, 0 clqs
(round 7, exhaustive) 21 del vars, 26 del conss, 0 add conss, 21 chg bounds, 9 chg sides, 0 chg coeffs, 0 upgd conss, 42 impls, 0 clqs
(round 8, exhaustive) 21 del vars, 26 del conss, 0 add conss, 21 chg bounds, 9 chg sides, 0 chg coeffs, 12 upgd conss, 42 impls, 0 clqs
(0.0s) probing cycle finished: starting next cycle
presolving (9 rounds: 9 fast, 3 medium, 3 exhaustive):
21 deleted vars, 26 deleted constraints, 0 added constraints, 21 tightened bounds, 0 added holes, 9 changed sides, 0 changed coefficients
88 implications, 1 cliques
presolved problem has 91 variables (11 bin, 0 int, 0 impl, 80 cont) and 97 constraints
12 constraints of type <varbound>
57 constraints of type <linear>
28 constraints of type <indicator>
transformed objective value is always integral (scale: 0.05)
Presolving Time: 0.00
time | node | left |LP iter|LP it/n|mem/heur|mdpt |vars |cons |rows |cuts |sepa|confs|strbr| dualbound | primalbound | gap | compl.
0.0s| 1 | 0 | 24 | - | 1144k | 0 | 91 | 97 | 41 | 0 | 0 | 0 | 0 | 0.000000e+00 | -- | Inf | unknown
0.0s| 1 | 0 | 30 | - | 1154k | 0 | 91 | 97 | 44 | 3 | 1 | 0 | 0 | 0.000000e+00 | -- | Inf | unknown
0.0s| 1 | 0 | 32 | - | 1169k | 0 | 91 | 97 | 46 | 5 | 2 | 0 | 0 | 0.000000e+00 | -- | Inf | unknown
0.0s| 1 | 0 | 34 | - | 1169k | 0 | 91 | 97 | 47 | 6 | 3 | 0 | 0 | 0.000000e+00 | -- | Inf | unknown
0.0s| 1 | 2 | 37 | - | 1177k | 0 | 91 | 97 | 47 | 6 | 5 | 0 | 0 | 0.000000e+00 | -- | Inf | unknown
d 0.0s| 33 | 12 | 133 | 3.6 |fracdivi| 10 | 91 | 101 | 52 | 0 | 2 | 4 | 0 | 1.350000e+00 | 3.000000e+00 | 122.22%| 14.25%
SCIP Status : problem is solved [optimal solution found]
Solving Time (sec) : 0.00
Solving Nodes : 47
Primal Bound : +3.00000000000000e+00 (1 solutions)
Dual Bound : +3.00000000000000e+00
Gap : 0.00 %
[linear] <c124>: <x6>[B] (+1) +<x7>[B] (+1) +<x15>[B] (+1) <= 2;
;
violation: right hand side is violated by 1
all 1 solutions given by solution candidate storage are infeasible
presolving:
(round 1, fast) 20 del vars, 18 del conss, 0 add conss, 18 chg bounds, 0 chg sides, 0 chg coeffs, 0 upgd conss, 40 impls, 0 clqs
(round 2, fast) 20 del vars, 18 del conss, 0 add conss, 18 chg bounds, 2 chg sides, 0 chg coeffs, 0 upgd conss, 42 impls, 0 clqs
(round 3, fast) 20 del vars, 18 del conss, 0 add conss, 20 chg bounds, 2 chg sides, 0 chg coeffs, 0 upgd conss, 42 impls, 0 clqs
(round 4, fast) 20 del vars, 19 del conss, 0 add conss, 20 chg bounds, 2 chg sides, 0 chg coeffs, 0 upgd conss, 42 impls, 0 clqs
(round 5, fast) 20 del vars, 19 del conss, 0 add conss, 21 chg bounds, 2 chg sides, 0 chg coeffs, 0 upgd conss, 42 impls, 0 clqs
(round 6, fast) 21 del vars, 20 del conss, 0 add conss, 21 chg bounds, 2 chg sides, 0 chg coeffs, 0 upgd conss, 42 impls, 0 clqs
(round 7, exhaustive) 21 del vars, 27 del conss, 0 add conss, 21 chg bounds, 9 chg sides, 0 chg coeffs, 0 upgd conss, 42 impls, 0 clqs
(round 8, exhaustive) 21 del vars, 27 del conss, 0 add conss, 21 chg bounds, 9 chg sides, 0 chg coeffs, 13 upgd conss, 42 impls, 0 clqs
(0.0s) probing cycle finished: starting next cycle
presolving (9 rounds: 9 fast, 3 medium, 3 exhaustive):
21 deleted vars, 27 deleted constraints, 0 added constraints, 21 tightened bounds, 0 added holes, 9 changed sides, 0 changed coefficients
90 implications, 2 cliques
presolved problem has 91 variables (11 bin, 0 int, 0 impl, 80 cont) and 98 constraints
12 constraints of type <varbound>
57 constraints of type <linear>
1 constraints of type <logicor>
28 constraints of type <indicator>
transformed objective value is always integral (scale: 0.05)
Presolving Time: 0.00
time | node | left |LP iter|LP it/n|mem/heur|mdpt |vars |cons |rows |cuts |sepa|confs|strbr| dualbound | primalbound | gap | compl.
0.0s| 1 | 0 | 19 | - | 1416k | 0 | 91 | 98 | 42 | 0 | 0 | 0 | 0 | 0.000000e+00 | -- | Inf | unknown
0.0s| 1 | 0 | 25 | - | 1432k | 0 | 91 | 98 | 45 | 3 | 1 | 0 | 0 | 0.000000e+00 | -- | Inf | unknown
0.0s| 1 | 0 | 27 | - | 1432k | 0 | 91 | 98 | 47 | 5 | 2 | 0 | 0 | 0.000000e+00 | -- | Inf | unknown
0.0s| 1 | 0 | 29 | - | 1432k | 0 | 91 | 98 | 48 | 6 | 3 | 0 | 0 | 0.000000e+00 | -- | Inf | unknown
0.0s| 1 | 2 | 32 | - | 1432k | 0 | 91 | 98 | 48 | 6 | 5 | 0 | 0 | 0.000000e+00 | -- | Inf | unknown
* 0.0s| 41 | 14 | 125 | 2.6 | LP | 9 | 91 | 98 | 51 | 12 | 2 | 6 | 0 | 2.500000e+00 | 3.900000e+00 | 56.00%| 27.86%
* 0.0s| 44 | 11 | 134 | 2.7 | LP | 9 | 91 | 98 | 50 | 13 | 2 | 6 | 0 | 2.500000e+00 | 3.550000e+00 | 42.00%| 29.72%
SCIP Status : problem is solved [optimal solution found]
Solving Time (sec) : 0.00
Solving Nodes : 55
Primal Bound : +3.55000000000000e+00 (2 solutions)
Dual Bound : +3.55000000000000e+00
Gap : 0.00 %
[linear] <c126>: <x5>[B] (+1) +<x6>[B] (+1) +<x7>[B] (+1) +<x9>[B] (+1) <= 3;
;
violation: right hand side is violated by 1
1/2 feasible solution given by solution candidate storage, new primal bound 3.900000e+00
presolving:
(round 1, fast) 20 del vars, 19 del conss, 0 add conss, 18 chg bounds, 0 chg sides, 0 chg coeffs, 0 upgd conss, 40 impls, 0 clqs
(round 2, fast) 20 del vars, 19 del conss, 0 add conss, 18 chg bounds, 2 chg sides, 0 chg coeffs, 0 upgd conss, 42 impls, 0 clqs
(round 3, fast) 20 del vars, 19 del conss, 0 add conss, 20 chg bounds, 2 chg sides, 0 chg coeffs, 0 upgd conss, 42 impls, 0 clqs
(round 4, fast) 20 del vars, 20 del conss, 0 add conss, 20 chg bounds, 2 chg sides, 0 chg coeffs, 0 upgd conss, 42 impls, 0 clqs
(round 5, fast) 20 del vars, 20 del conss, 0 add conss, 21 chg bounds, 2 chg sides, 0 chg coeffs, 0 upgd conss, 42 impls, 0 clqs
(round 6, fast) 21 del vars, 21 del conss, 0 add conss, 21 chg bounds, 2 chg sides, 0 chg coeffs, 0 upgd conss, 42 impls, 0 clqs
(round 7, exhaustive) 21 del vars, 28 del conss, 0 add conss, 21 chg bounds, 9 chg sides, 0 chg coeffs, 0 upgd conss, 42 impls, 0 clqs
(round 8, exhaustive) 21 del vars, 28 del conss, 0 add conss, 21 chg bounds, 9 chg sides, 0 chg coeffs, 14 upgd conss, 42 impls, 0 clqs
(0.0s) probing cycle finished: starting next cycle
presolving (9 rounds: 9 fast, 3 medium, 3 exhaustive):
21 deleted vars, 28 deleted constraints, 0 added constraints, 21 tightened bounds, 0 added holes, 9 changed sides, 0 changed coefficients
90 implications, 2 cliques
presolved problem has 91 variables (11 bin, 0 int, 0 impl, 80 cont) and 99 constraints
12 constraints of type <varbound>
57 constraints of type <linear>
2 constraints of type <logicor>
28 constraints of type <indicator>
transformed objective value is always integral (scale: 0.05)
Presolving Time: 0.00
transformed 1/1 original solutions to the transformed problem space
time | node | left |LP iter|LP it/n|mem/heur|mdpt |vars |cons |rows |cuts |sepa|confs|strbr| dualbound | primalbound | gap | compl.
0.0s| 1 | 0 | 15 | - | 1948k | 0 | 91 | 99 | 43 | 0 | 0 | 0 | 0 | 0.000000e+00 | 3.900000e+00 | Inf | unknown
0.0s| 1 | 0 | 21 | - | 1964k | 0 | 91 | 99 | 46 | 3 | 1 | 0 | 0 | 0.000000e+00 | 3.900000e+00 | Inf | unknown
0.0s| 1 | 0 | 23 | - | 1964k | 0 | 91 | 99 | 48 | 5 | 2 | 0 | 0 | 0.000000e+00 | 3.900000e+00 | Inf | unknown
0.0s| 1 | 0 | 25 | - | 1964k | 0 | 91 | 99 | 49 | 6 | 3 | 0 | 0 | 0.000000e+00 | 3.900000e+00 | Inf | unknown
0.0s| 1 | 2 | 28 | - | 1965k | 0 | 91 | 99 | 49 | 6 | 5 | 0 | 0 | 0.000000e+00 | 3.900000e+00 | Inf | unknown
SCIP Status : problem is solved [optimal solution found]
Solving Time (sec) : 0.00
Solving Nodes : 83
Primal Bound : +3.90000000000000e+00 (1 solutions)
Dual Bound : +3.90000000000000e+00
Gap : 0.00 %
28 constraints of type <indicator>
transformed objective value is always integral (scale: 0.05)
Presolving Time: 0.00
time | node | left |LP iter|LP it/n|mem/heur|mdpt |vars |cons |rows |cuts |sepa|confs|strbr| dualbound | primalbound | gap | compl.
0.0s| 1 | 0 | 22 | - | 3052k | 0 | 91 | 100 | 44 | 0 | 0 | 0 | 0 | 0.000000e+00 | -- | Inf | unknown
0.0s| 1 | 0 | 26 | - | 3067k | 0 | 91 | 100 | 47 | 3 | 1 | 0 | 0 | 0.000000e+00 | -- | Inf | unknown
0.0s| 1 | 0 | 28 | - | 3067k | 0 | 91 | 100 | 49 | 5 | 2 | 0 | 0 | 0.000000e+00 | -- | Inf | unknown
0.0s| 1 | 0 | 30 | - | 3067k | 0 | 91 | 100 | 50 | 6 | 3 | 0 | 0 | 0.000000e+00 | -- | Inf | unknown
0.0s| 1 | 2 | 33 | - | 3067k | 0 | 91 | 100 | 50 | 6 | 5 | 0 | 0 | 0.000000e+00 | -- | Inf | unknown
SCIP Status : problem is solved [infeasible]
Solving Time (sec) : 0.00
Solving Nodes : 47
Primal Bound : +1.00000000000000e+20 (0 solutions)
Dual Bound : +1.00000000000000e+20
Gap : 0.00 %
Thanks a lot, I confirm I can reproduce this with the LP file (the error does not appear with the MPS on my side)
However, I have to say that PySCIPOpt does a terrible job at catching errors. Virtually every bit from SCIP that goes into the error stream kills your Python program, which makes debugging very tedious. The PySCIPOpt documentation is minimalistic and adds only very little to the SCIP docs.
Sorry, for completeness:
- with the LP file, I get the ELEAVE56 error but eventually solution optimal
- with the MPS file, I get problem infeasible
What is the "expected" status for this problem?
Optimal (minimal) with value 3 (just take the solution of SCIP 8.0.0 if unsure) Example vector:
x000 = 0.0
x001 = 0.0
x002 = 0.0
x003 = 0.0
x004 = 0.0
x005 = 1.0
x006 = 1.0
x007 = 0.0
x008 = 0.0
x009 = 0.0
x010 = 0.0
x011 = 0.0
x012 = 0.0
x013 = 0.0
x014 = 1.0
x015 = 1.0
x016 = 1.0
x017 = 1.0
x018 = 1.0
x019 = 1.0
x020 = 1.0
x021 = 0.0
x022 = 1.0
x023 = 0.0
x024 = 1.0
x025 = 0.0
x026 = 0.0
x027 = 2.0
x028 = 0.0
x029 = 0.0
x030 = 2.0
x031 = 0.0
x032 = 0.0
x033 = 0.0
x034 = 0.0
x035 = 0.0
x036 = 0.0
x037 = 0.0
x038 = 0.0
x039 = 0.0
x040 = 0.0
x041 = 0.0
x042 = 0.0
x043 = 0.0
x044 = 0.0
x045 = 0.0
x046 = 0.0
x047 = 0.0
x048 = 0.0
x049 = 0.0
x050 = 0.0
x051 = 0.0
x052 = 0.0
x053 = 0.0
x054 = 0.8
x055 = 0.0
x056 = 0.0
x057 = 0.0
x058 = 4.5
x059 = 4.5
x060 = 0.0
x061 = 0.0
x062 = 0.0
x063 = 4.5
x064 = 0.0
x065 = 0.0
x066 = 0.0
x067 = 9.0
x068 = 4.5
x069 = 4.5
x070 = 0.0
x071 = 4.5
x072 = 0.0
x073 = 0.0
x074 = 0.0
x075 = 0.0
x076 = 0.0
x077 = 0.0
x078 = 0.0
x079 = 0.0
x080 = 0.0
x081 = 0.0
x082 = 0.0
x083 = 2.0
x084 = 0.0
x085 = 0.0
x086 = 0.0
x087 = 0.0
x088 = 2.0
x089 = 0.0
x090 =-2.0
x091 = 0.0
x092 = 0.0
x093 = 0.0
x094 = 0.0
x095 = 0.0
x096 = 0.0
x097 = 0.0
x098 = 0.0
x099 = 0.0
x100 = 0.0
x101 = 0.0
x102 = 0.0
x103 = 0.0
x104 = 2.0
hi @VonAlphaBisZulu, SCIP 8.0.2 was released so I rechecked your issue, it seems that the LP file always finds a solution for me.
The MPS I now have a consistent failure for some reason. Can you check whether v8.0.2 fixed your issue?
SCIP 8.0.2 did not fix my issue:
For completeness, again the zip: scip_issue_23.zip containing the identical problem as mps and lp file.
- scip_issue_23.mps
- scip_issue_23.lp
Procedure to solve these:
- start scip
- read /path/to/scip_issue_23.mps or /path/to/scip_issue_23.lp
- optimize
Solving yields:
| File | SCIP 8.0.0 | SCIP 8.0.1 | SCIP 8.0.2 |
|---|---|---|---|
| scip_issue_23.lp | $\textcolor{green}{\text{optimal (optval=3) }}$ | $\textcolor{orange}{\text{optimal (optval=3) but raises ELEAVE56 ERROR! }}$ | $\textcolor{orange}{\text{optimal (optval=3) but raises ELEAVE56 ERROR! }}$ |
| scip_issue_23.mps | $\textcolor{green}{\text{optimal (optval=3) }}$ | $\textcolor{red}{\text{stalls at ELEAVE56 ERROR! }}$ | $\textcolor{red}{\text{stalls at ELEAVE56 ERROR! }}$ |
I get a different behavior and am wondering what could lead to this. How did you build SCIP here? With PaPILO? If you have the executable, you can just run the binary and show the header
I tested on, Windows 11 and WSL2 with Ubuntu 20.04. In both cases, I installed scip through conda, simply with the command:
conda install -c conda-forge scip=8.0.2
Headers are in Windows (with python 3.7.12):
SCIP version 8.0.2 [precision: 8 byte] [memory: block] [mode: optimized] [LP solver: Soplex 6.0.2] [GitHash: 5f0473c4fb]
Copyright (C) 2002-2022 Konrad-Zuse-Zentrum fuer Informationstechnik Berlin (ZIB)
External libraries:
Soplex 6.0.2 Linear Programming Solver developed at Zuse Institute Berlin (soplex.zib.de) [GitHash: 45f6420d]
CppAD 20180000.0 Algorithmic Differentiation of C++ algorithms developed by B. Bell (github.com/coin-or/CppAD)
ZLIB 1.2.12 General purpose compression library by J. Gailly and M. Adler (zlib.net)
AMPL/MP 4e2d45c4 AMPL .nl file reader library (github.com/ampl/mp)
PaPILO 2.1.1 parallel presolve for integer and linear optimization (github.com/scipopt/papilo) [GitHash: 01fada2]
bliss 0.77 Computing Graph Automorphism Groups by T. Junttila and P. Kaski (www.tcs.hut.fi/Software/bliss/)
Ipopt 3.14.10 Interior Point Optimizer developed by A. Waechter et.al. (github.com/coin-or/Ipopt)
In WSL (with python 3.9.13):
SCIP version 8.0.2 [precision: 8 byte] [memory: block] [mode: optimized] [LP solver: Soplex 6.0.2] [GitHash: 5f0473c4fb]
Copyright (C) 2002-2022 Konrad-Zuse-Zentrum fuer Informationstechnik Berlin (ZIB)
External libraries:
Soplex 6.0.2 Linear Programming Solver developed at Zuse Institute Berlin (soplex.zib.de) [GitHash: 45f6420d]
CppAD 20180000.0 Algorithmic Differentiation of C++ algorithms developed by B. Bell (github.com/coin-or/CppAD)
ZLIB 1.2.12 General purpose compression library by J. Gailly and M. Adler (zlib.net)
GMP 6.2.1 GNU Multiple Precision Arithmetic Library developed by T. Granlund (gmplib.org)
ZIMPL 3.5.3 Zuse Institute Mathematical Programming Language developed by T. Koch (zimpl.zib.de)
AMPL/MP 4e2d45c4 AMPL .nl file reader library (github.com/ampl/mp)
PaPILO 2.1.1 parallel presolve for integer and linear optimization (github.com/scipopt/papilo) [GitHash: 01fada2]
bliss 0.77 Computing Graph Automorphism Groups by T. Junttila and P. Kaski (www.tcs.hut.fi/Software/bliss/)
Ipopt 3.14.10 Interior Point Optimizer developed by A. Waechter et.al. (github.com/coin-or/Ipopt)
Results in terms of errors and optimal values are identical in Windows and Linux for me.
ok interesting, in debug mode I systematically get
scip: /scratch/opt/mbesanco/scip-dev/scip/src/scip/cons_indicator.c:3419: presolRoundIndicator: Assertion `SCIPconsGetNUpgradeLocks(consdata->lincons) == 0' failed.
no matter the version
I'll check now what I get in release mode, it might be that the assert removed leads to something incorrect
this is a tough one, for a bit of swapping through version combinations, it seems the culprit for the warning is the new soplex version, not the new SCIP.
But it also seems that additional checks in debug modes were always throwing an error for the MPS, both for v800 and v802
As a mere user, I am not familiar with the SCIP code and building process. Just to express my thoughts: "ELEAVE56 ERROR! Tried to put a fixed column variable into the basis." should be caught and, if anything, raise a warning. The user has no way to avoid this, and when solving the identical problem from an LP-file, the solver continues after ELEAVE56. I'm sure you'll come up with a good solution.
Yes I agree that something should be caught by the solver, what it is exactly is still unclear to me. I tried something different here, taking the MPS file and reading it through JuMP, the model produced by JuMP is valid and produces the expected optimal solution without any error nor assert in debug
Should I create an issue in the SoPlex repo?
no need, I think something should be handled on the SCIP side in any case
the question the last point raises is whether the problem in the MPS is well-formed, in which case it is the model construction part that is at fault
@VonAlphaBisZulu the issue is solved with the LP file it seems, the MPS still causes the same issue, when using 8.0.3
Hello everyone!
I am having the same issue but I couldn't understand If you had found a solution.
Any help is welcomed
