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<span style="font-family: Calibri, Helvetica, sans-serif;">Hi,</span></div>
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<span style="font-family: Calibri, Helvetica, sans-serif;">I would like to ask how the dual bound is updated in the SCIP branch and price framework.</span></div>
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<span style="color: rgb(0, 0, 0); font-family: Calibri, Helvetica, sans-serif; font-size: 12pt;">When the columns generated at the root node, LP obj value decrease. </span></div>
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<span style="color: rgb(0, 0, 0); font-family: Calibri, Helvetica, sans-serif; font-size: 12pt;">Thus, I expected dual bound would also be decreased. It was true for some instances but </span><span style="color: rgb(0, 0, 0); font-family: Calibri, Helvetica, sans-serif; font-size: 12pt;">it
doesn't seem to be always this case.</span></div>
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<span style="color: rgb(0, 0, 0); font-family: Calibri, Helvetica, sans-serif; font-size: 12pt;">For example, the following is a initial part of output logs of the column generation at the root node.</span></div>
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<span style="color: rgb(0, 0, 0); font-family: Calibri, Helvetica, sans-serif; font-size: 12pt;">Here, "Depth: 0" means it is at the root node and "LPObj" value is SCIPgetLPObjval</span></div>
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<span style="font-family: Calibri, Helvetica, sans-serif;"><i> Starts CG at a new node: 1. (Depth: 0, LPObj: 11358.02, Parent: 0, Branched var in the parent node: None)</i></span></div>
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<span style="font-family: Calibri, Helvetica, sans-serif;"><i> time | node | left |LP iter |LP it/n|mem/heur|mdpt |vars |cons |rows |cuts |sepa|confs|strbr| dualbound | primalbound | gap | compl.
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<div><span style="font-family: Calibri, Helvetica, sans-serif;"><i> 81.1s | 1 | 0 | 8064 | - | 462M | 0 | 78k| 108k| 108k| 0 | 0 | 0 | 0 | 1.135802e+04 | -- | Inf | unknown</i></span></div>
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<span style="font-family: Calibri, Helvetica, sans-serif;"><i>o 146s| 1 | 0 | 14010 | - |feaspump| 0 | 78k| 108k| 108k| 0 | 0 | 0 | 0 | 1.135802e+04 | 5.000000e+04 | 340.22%| unknown</i></span></div>
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<span style="font-family: Calibri, Helvetica, sans-serif;"><i> L Continues CG at the curr node: 1, (Depth: 0, LPObj: 6668.00, N(new columns so far): 1. )</i></span>
<div><font face="Calibri, Helvetica, sans-serif"><i> L Continues CG at the curr node: 1, (Depth: 0, LPObj: 4940.83, N(new columns so far): 2. )
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<div style="font-size: 12pt; color: rgb(0, 0, 0);"><font face="Calibri, Helvetica, sans-serif"><i>... (omitted)</i></font></div>
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<div style="font-size: 12pt; color: rgb(0, 0, 0);"><font face="Calibri, Helvetica, sans-serif"><i> L Continues CG at the curr node: 1, (Depth: 0, LPObj: 5.57, N(new columns so far): 11. )
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<div style="font-size: 12pt; color: rgb(0, 0, 0);"><font face="Calibri, Helvetica, sans-serif"><i> 346s| 1 | 0 | 26166 | - | 497M | 0 | 78k| 108k| 108k| 3 | 1 | 0 | 0 | 1.135802e+04 | 5.000000e+04 | 340.22%| unknown</i></font></div>
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LPObj decreases as new columns added, but the dual bound stays at 11358.02 which is the initial LPObj. </div>
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Isn't the dual bound supposed to be 5.57 after adding 11th columns? </div>
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T<span style="color: rgb(0, 0, 0); font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt;">hen, once the branching starts the following assertion error appears.</span></div>
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<span>scipoptsuite-7.0.0/scip/src/scip/tree.c:2457: SCIPnodeSetEstimate: Assertion `SCIPsetIsRelGE(set, newestimate, node->lowerbound)' failed.<br>
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<span>I guess this assertion error relates to the large gap between LPObj and the dual bound. </span></div>
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<span>Thank you.</span></div>
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