Mike wants to invest in $X_1$ if and only if he invests into $X_2$ or $X_3$ or both.
Please help i can't get my head around this
Thanks
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$\begingroup$ Something like $X_1\geq \frac12\left(X_2+X_3 \right), \ \ X_1,X_2,X_3\in\{0,1\}$. But additional the objective function has to be known. $\endgroup$callculus42– callculus422018-11-14 13:15:32 +00:00Commented Nov 14, 2018 at 13:15
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1 Answer
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The constraint $$ X_1 \geq \frac12 (X_2 + X_3) $$ would ensure that $X_1$ is one if either is one. On the other hand: $$ X_1 \leq X_2 + X_3 $$ would ensure that $X_1$ is zero if both are zero.
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1$\begingroup$ In your second inequality $\frac{1}{2}$ can be removed. There is also a typo ($X_1$ on the right hand side should be $X_3$) $\endgroup$user477602– user4776022018-11-14 13:32:21 +00:00Commented Nov 14, 2018 at 13:32