Objective Coefficient Rounding and Almost Symmetries in Binary Programs
This article investigates the interplay of rounding objective coefficients in binary programs and almost symmetries. Empirically, reducing the number of significant bits through rounding often leads to instances that are easier to solve. One reason can be that the amount of symmetries increases, which enables solvers to be more effective when they are exploited. This can signify that the original instance contains 'almost symmetries'. Furthermore, solving the rounded problems provides approximations to the original objective values. We empirically investigate these relations on instances of the capacitated facility location problem, the knapsack problem and a diverse collection of additional instances, using the solvers SCIP and CP-SAT. For all investigated problem classes, we show empirically that this yields faster algorithms with guaranteed solution quality. The influence of symmetry depends on the instance type and solver.