Tightening methods based on nontrivial bounds on bilinear terms

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We develop tightening and solution methods for optimization problems containing bilinear terms. We focus on the bilinear term w= xy with nonnegative variables x∈ [xL, xU] and y∈ [yL, yU] , where w is semi-continuous and upper and lower bounded by wU and wL when positive. wU and wL are said to be nontrivial upper and lower bounds if wU is smaller than xUyU and wL is greater than xLyL, respectively. We derive a family of valid linear constraints and show that, when one of the nontrivial bounds is active, such constraints are tangent to one branch of the hyperbola that represents the bilinear term. We propose different preprocessing methods for generating strong constraints from the family. Computational results demonstrate the effectiveness of the proposed methods in terms of reducing optimality gap and computational time.

Original languageEnglish (US)
Pages (from-to)1217-1254
Number of pages38
JournalOptimization and Engineering
Issue number3
StatePublished - Sep 2022

All Science Journal Classification (ASJC) codes

  • Software
  • Civil and Structural Engineering
  • Aerospace Engineering
  • Mechanical Engineering
  • Control and Optimization
  • Electrical and Electronic Engineering


  • Nonconvex optimization
  • Nonlinear optimization
  • Preprocessing
  • Semi-continuous variables
  • Valid constraints


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