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<p style="margin-top:0;margin-bottom:0">Hello SCIP team,</p>
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<p style="margin-top:0;margin-bottom:0">I am using disjunction constraints a lot and performance variability which may go beyond the issue of simply reordering the decision variables and constraints. Performance varies significantly with other seemingly minor
model reformulations. </p>
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<p style="margin-top:0;margin-bottom:0">Some people have suggested this might be because they hypothesize that the disjunction constraints use Big M which has weak linear relaxations. </p>
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<p style="margin-top:0;margin-bottom:0">But I don't think it uses Big M. My understanding is that the way disjuncts work is that each disjunct is added to the local search problem which seems like a totally different approach than using Big M, and also didn't
see anything about Big M in my brief review of the disjunct constraint source code. </p>
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<p style="margin-top:0;margin-bottom:0">My questions are:</p>
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<li>Does disjunction constraint handler rely in Big-M reformulation?</li><li>Are there <span style="font-size: 12pt;">any particular search control options which are particularly well (or poorly) suited for disjunction constraints?</span></li></ul>
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<p style="margin-top:0;margin-bottom:0"><span style="font-size: 12pt;">Thanks,</span></p>
<p style="margin-top:0;margin-bottom:0"><span style="font-size: 12pt;"> Rich Levinson</span></p>
<p style="margin-top:0;margin-bottom:0"><span style="font-size: 12pt;"> NASA Ames Research Center.</span></p>
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