I have an association matrix $n\times n$ where the values are either $0$ or $1$. So this matrix is called $B$ and $b(ij)$ is either $0$ or $1$ . However when $i=0$ this means something and if $i>0$ it means something else. How can I express this in a mathematical model?
How to represent a decision variable?
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mathematical-modeling
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0I think you just did. – 2017-02-05
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0I mean representing it in a mathematical way that is without really explaining all this for example like this \begin{cases} 0, & \text{if i =0 case1}\ \\ 0, & \text{if i >0 case2}\ \\ 1, & \text{otherwise} \end{cases} – 2017-02-05
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0I'm assuming, given the matrix of dimension $n\times n$, that both $1\leq i\leq n$, and $1\leq j\leq n$. The indices of entry b( i, j ) give the ith row and the jth column of the entry, not the value of the entry. So could you explain what you mean by the case in which $i = 0$? – 2017-02-05
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0@amWhy I actually considered that the indices start from zero so by i=0 and mean i=1 – 2017-02-05
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0So if i=1 it represent something and if i >1 it represent something else. For example i=1 represent the column for a unique cat and i>1 represent the columns for the different dogs I have. If a1j =1 then this means that boy number j likes the cat and if a(ij) =1 that means that the boy number j likes the dog number i – 2017-02-05
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0$i$ usually identifies the row of the matrix, j the column of the matrix. – 2017-02-05
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0@amWhy yes indeed – 2017-02-05