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Author: fwesselm

highs/presolve/HPresolve.cpp

@@ -4197,7 +4197,14 @@ HPresolve::Result HPresolve::detectDominatedCol(
                                   : -impliedDualRowBounds.getSumLowerOrig(
                                         col, -model->col_cost_[col]);
       if (boundOnColDual == 0.0) {
-        // remove column and rows
+        // 1. column's lower bound is infinite (i.e. column dual has upper bound
+        // of zero) and column dual's lower bound is zero as well
+        // (direction = 1) or
+        // 2. column's upper bound is infinite (i.e. column dual has lower bound
+        // of zero) and column dual's upper bound is zero as well
+        // (direction = -1).
+        // thus, the column dual is zero, and we can remove the column and
+        // all its rows
         if (logging_on) analysis_.startPresolveRuleLog(kPresolveRuleForcingCol);
         postsolve_stack.forcingColumn(
             col, getColumnVector(col), model->col_cost_[col], otherBound,