maximize obj: + x4 + x1 + x2 + x3 subject to constraint1: + 2 x1 - x2 + c1 <= 1 constraint2: - x1 + 2 x2 - x3 + c2 <= 1 constraint3: - x2 + 2 x3 - x4 + c3 <= 1 constraint4: - x3 + 2 x4 + c4 <= 1 bounds 2 <= c1 <= 2 0 <= c2 <= 0 0 <= c3 <= 0 0 <= c4 <= 0 generals x1 x2 x3 x4 c1 c2 c3 c4 end