[Scip] SCIP v3.2.0 Hanging on Problem

[Jonathan Currie]

Hi All,

The attached problem hangs (well, fails to make any reasonable progress) in my latest build of SCIP v3.2 with default settings. Original problem:

Min     -x(1)*x(2)*x(3)*x(4)
s.t.    x(1)^3 + x(2)^2 - 1 == 0
          x(1)^2*x(4) - x(3) == 0
          x(4)^2 - x(2) == 0

Any ideas?

Thanks,
Jonathan

SCIP: Solving Constraint Integer Programs [v3.2.0, Built Jul  2 2015, VS2013]
  - SoPlex [v220] (ZIB Academic License)
  - Ipopt  [v3.12.3] (Eclipse Public License)
  - CppAD  [v20140000.3] (Eclipse Public License)

presolving:
(round 1, fast)       0 del vars, 0 del conss, 0 add conss, 1 chg bounds, 0 chg sides, 0 chg coeffs, 1 upgd conss, 0 impls, 0 clqs
(round 2, fast)       0 del vars, 0 del conss, 0 add conss, 2 chg bounds, 0 chg sides, 0 chg coeffs, 1 upgd conss, 0 impls, 0 clqs
(round 3, fast)       0 del vars, 0 del conss, 4 add conss, 2 chg bounds, 0 chg sides, 0 chg coeffs, 1 upgd conss, 0 impls, 0 clqs
(round 4, fast)       0 del vars, 0 del conss, 4 add conss, 3 chg bounds, 0 chg sides, 0 chg coeffs, 7 upgd conss, 0 impls, 0 clqs
(round 5, fast)       0 del vars, 0 del conss, 4 add conss, 4 chg bounds, 0 chg sides, 0 chg coeffs, 8 upgd conss, 0 impls, 0 clqs
presolving (6 rounds: 6 fast, 1 medium, 1 exhaustive):
 0 deleted vars, 0 deleted constraints, 4 added constraints, 4 tightened bounds, 0 added holes, 0 changed sides, 0 changed coefficients
 0 implications, 0 cliques
presolved problem has 9 variables (0 bin, 0 int, 0 impl, 9 cont) and 8 constraints
      2 constraints of type <abspower>
      6 constraints of type <quadratic>
Presolving Time: 0.00

 time | node  | left  |LP iter|LP it/n| mem |mdpt |frac |vars |cons |cols |rows |cuts |confs|strbr|  dualbound   | primalbound  |  gap   
  0.0s|     1 |     0 |     0 |     - | 219k|   0 |   - |   9 |   8 |   9 |  10 |   0 |   0 |   0 |      --      |      --      |    Inf 

******************************************************************************
This program contains Ipopt, a library for large-scale nonlinear optimization.
 Ipopt is released as open source code under the Eclipse Public License (EPL).
         For more information visit http://projects.coin-or.org/Ipopt
******************************************************************************

  0.1s|     1 |     0 |     2 |     - | 223k|   0 |   - |   9 |   8 |   9 |  11 |   1 |   0 |   0 |      --      |      --      |    Inf 
(node 1) LP relaxation is unbounded (LP 1)
q 0.1s|     1 |     0 |    15 |     - | 225k|   0 |   - |   9 |   8 |   9 |  11 |   1 |   0 |   0 |      --      |0.000000e+000 |    Inf 
  0.1s|     1 |     0 |    15 |     - | 225k|   0 |   - |   9 |   8 |   9 |  11 |   1 |   0 |   0 |      --      |0.000000e+000 |    Inf 
(node 1) LP relaxation is unbounded (LP 4)
  0.1s|     1 |     2 |    15 |     - | 224k|   0 |   - |   9 |   8 |   9 |  11 |   1 |   0 |   0 |      --      |0.000000e+000 |    Inf 
y 0.1s|     2 |     1 |    15 |  13.0 | 224k|   1 |   - |   9 |   8 |   0 |   0 |   1 |   0 |   0 |      --      |-2.500000e-001 |    Inf 
  0.2s|   100 |    77 |    40 |   0.4 | 254k|  77 |   - |   9 |   8 |   9 |   0 |  26 |   0 |   0 |      --      |-2.500000e-001 |    Inf 
  0.2s|   200 |    45 |    40 |   0.2 | 259k| 112 |   - |   9 |   8 |   0 |   0 |  26 |   0 |   0 |      --      |-2.500000e-001 |    Inf 
  0.3s|   300 |    65 |    40 |   0.1 | 273k| 171 |   - |   9 |   8 |   9 |   0 |  26 |   0 |   0 |      --      |-2.500000e-001 |    Inf 
  0.3s|   400 |   153 |   555 |   1.4 | 372k| 255 |   0 |   9 |   8 |   9 |  79 | 574 |   0 |   0 |      --      |-2.500000e-001 |    Inf 

SCIP Status        : solving was interrupted [time limit reached]
Solving Time (sec) : 1000.00
Solving Nodes      : 415
Primal Bound       : -2.50000000000035e-001 (2 solutions)
Dual Bound         : -1.00000000000000e+020
Gap                : infinite
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