<div dir="ltr"><div><div><div>Dear all,<br><br></div>I have a branch and price algorithm. I am facing a problem when I use the barrier method to solve the master problem. I was hoping that you can help me. <br>When I set both "lp/initalgorithm" and "lp/resolvealgorithm" to barrier method, in most cases It stops with : (I have copied a little longer version of the lof file at the end of the email)<br><br><span style="color:rgb(61,133,198)"><span style="background-color:rgb(243,243,243)"><span style="color:rgb(68,68,68)">Barrier limit on dual objective exceeded.<br> Infeasible barrier solution (dependent on objective limit).<br><br>src/scip/lp.c:14237: lpSolve: Assertion `!(set->lp_disablecutoff == 1
|| (set->nactivepricers > 0 && set->lp_disablecutoff
== 2))' failed.<span style="background-color:rgb(255,255,255)"><span style=""></span></span></span><br><br></span></span></div><span style="color:rgb(61,133,198)"><span style="background-color:rgb(243,243,243)"><span style="background-color:rgb(255,255,255)"><font color="#000000">I could not find a parameter such as barrier objective limit</font>. <font color="#000000">I used SCIPsetObjlimit</font> <span style="color:rgb(0,0,0)">to set a higher objective limit ( I am not sure if the limit this function is setting is the same as the barrier objective limit)</span></span>.<span style="background-color:rgb(255,255,255)"><span style="color:rgb(0,0,0)"> This time it gives the following line as well:</span></span></span></span><br><span style="color:rgb(61,133,198)"><span style="background-color:rgb(243,243,243)"><span style="color:rgb(61,133,198)"><span style="background-color:rgb(243,243,243)"><span style="color:rgb(68,68,68)">src/scip/lp.c:14237: lpSolve: Assertion `!(set->lp_disablecutoff == 1
|| (set->nactivepricers > 0 && set->lp_disablecutoff
== 2))' failed.<span style="background-color:rgb(255,255,255)"><span style=""><br><br></span></span></span></span></span></span></span></div><span style="color:rgb(61,133,198)"><span style="background-color:rgb(243,243,243)"><span style="background-color:rgb(255,255,255)"><span style=""><font color="#000000">For a few instances</font></span></span><span style="color:rgb(0,0,0)">, setting only </span></span></span><span style="color:rgb(0,0,0)">"</span>lp/initalgorithm" to barrier and leaving "lp/resolvealgorithm" to its default value solves the problem. I should also mention that this problem does not happen when master problem is solved with Simplex.<br><span style="color:rgb(61,133,198)"><span style="background-color:rgb(243,243,243)"><span style=""></span></span></span><br><div><div><div><div>The log file when "lp/initalgorithm" = 'b' and "lp/resolvealgorithm"= 'b':<br><span style="background-color:rgb(238,238,238)"><span style="color:rgb(102,102,102)">Iteration log . . .<br>Iteration: 1 Dual objective = 10.330177<br>Tried aggregator 1 time.<br>LP Presolve eliminated 42 rows and 244 columns.<br>Aggregator did 19 substitutions.<br>Reduced LP has 78 rows, 119 columns, and 599 nonzeros.<br>Presolve time = 0.00 sec. (0.33 ticks)<br>Parallel mode: using up to 5 threads for barrier.<br>Number of nonzeros in lower triangle of A*A' = 494<br>Using Approximate Minimum Degree ordering<br>Total time for automatic ordering = 0.00 sec. (0.03 ticks)<br>Summary statistics for Cholesky factor:<br> Threads = 5<br> Rows in Factor = 78<br> Integer space required = 115<br> Total non-zeros in factor = 841<br> Total FP ops to factor = 10747<br> Itn Primal Obj Dual Obj Prim Inf Upper Inf Dual Inf Inf Ratio<br> 0 1.6080489e+04 -1.4387026e+02 2.85e+02 1.01e+02 2.25e+03 1.00e+00<br> 1 1.4132721e+04 -3.4691316e+02 2.52e+02 8.88e+01 1.23e+03 1.83e-01<br> 2 1.4278598e+04 -5.9373199e+02 2.56e+02 9.01e+01 1.30e+03 1.20e-01<br> 3 9.9158960e+03 -1.7167304e+03 1.94e+02 6.84e+01 8.37e+02 4.26e-02<br> 4 5.0149903e+02 -9.9732945e+02 2.01e+01 7.07e+00 3.08e+02 8.41e-02<br> 5 1.3386365e+02 -2.0932657e+02 4.66e+00 1.64e+00 7.00e+01 3.80e-01<br> 6 3.2369401e+01 -3.3609945e+01 8.79e-01 3.10e-01 1.36e+01 2.14e+00<br> 7 2.1874403e+01 -1.7917016e+01 5.50e-01 1.94e-01 7.97e+00 3.46e+00<br> 8 1.6189845e+01 7.2562159e+00 2.76e-01 9.73e-02 9.12e-01 1.44e+01<br> 9 2.8249210e+01 1.6791221e+01 3.35e-01 1.18e-01 1.09e+00 6.18e+00<br> 10 4.5434437e+01 5.6716247e+01 3.38e-01 1.19e-01 1.11e+00 3.23e+00<br> 11 4.9392601e+01 6.6979256e+01 3.20e-01 1.13e-01 9.47e-01 1.53e+00<br> 12 5.6458356e+01 9.9330286e+01 3.09e-01 1.09e-01 8.07e-01 5.59e-01<br> 13 2.2191704e+02 1.0781431e+02 3.05e-01 1.07e-01 8.07e-01 2.03e-02<br> 14 8.6508663e+01 1.0162578e+02 2.74e-01 9.64e-02 7.82e-01 6.30e-03<br> 15 3.3035441e+02 7.4121836e+05 2.74e-01 9.66e-02 8.71e-01 8.24e-05<br> 16 2.5380932e+02 1.7310730e+08 2.99e-01 1.06e-01 5.31e+00 2.59e-08<br> 17 1.7742307e+02 3.5154843e+11 2.75e-01 9.69e-02 3.96e+04 3.27e-12<br> 18 1.6774322e+02 3.0499215e+15 2.72e-01 9.59e-02 4.97e+08 3.28e-16<br> 19 1.6803927e+02 2.9430527e+19 2.61e-01 9.19e-02 1.17e+13 3.40e-20<br> 20 1.6131741e+02 2.7393729e+23 2.57e-01 8.61e-02 5.92e+16 4.39e-24<br> * 1.6803927e+02 2.9430527e+19 2.61e-01 9.19e-02 1.17e+13 3.40e-20<br> Barrier limit on dual objective exceeded.<br> Infeasible barrier solution (dependent on objective limit).<br>Barrier time = 0.11 sec. (1.56 ticks)<span style=""></span><br><br>Total time on 5 threads = 0.11 sec. (1.56 ticks)<br>vaccine: src/scip/lp.c:14237: lpSolve: Assertion `!(set->lp_disablecutoff == 1 || (set->nactivepricers > 0 && set->lp_disablecutoff == 2))' failed.<br><br><br><br></span></span></div><div><span style="background-color:rgb(238,238,238)"><span style="color:rgb(102,102,102)"><span style="color:rgb(0,0,0)"><span style="background-color:rgb(255,255,255)">Thanks</span></span><span style="background-color:rgb(255,255,255)"><span style=""><font color="#000000">.</font></span></span><br></span></span></div><div><div><br></div></div></div></div></div></div>