Logical OR

d = max {d₁, d₂} for two binary variables d₁, d₂, or
d = d₁ OR d₂ as a logical expression

• IP formulation

  d ≥ d1	[1.1]
  d ≥ d2	[1.2]
  d ≤ d1 + d2	[2]
  d ≤ 1	[3]

• Generalization to d = max {d₁, d₂ , ..., d_n}

  d ≥ di	[1.i]
  d ≤ ∑i di	[2.i]
  d ≤ 1	[3]

  Note: equivalent to d = d₁ OR d₂ ... OR d_n
• See Section Boolean variables for an alternative formulation via Boolean variables