I am working in constraint optimization. And I've just come across this notation.

I'm not sure what this means.

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The set I is the set of inequality constraints. I'm not sure what the function in brackets means

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    $\begingroup$ Any more context you can give would be helpful. I don't know about the specific field of constraint optimisation, but that kind of notation in other areas is usually defined ad-hoc. $\endgroup$ – Patrick Stevens Dec 20 '17 at 23:20

I guess that $[y]^- = \min(y,0)$.

This notation is mentioned in Wikipedia, but with a slight difference: $[y]^- = -\min(y,0)$.

The important point is the minus sign as a superscript. The brackets are just like parentheses.

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  • $\begingroup$ Other interpretations are possible, namely $\min(\lfloor y\rfloor ,0 )$ and $\min(\text{round}(y),0)$, where $\text{round}$ denotes the closest integer. $\endgroup$ – Jack D'Aurizio Dec 21 '17 at 1:27
  • $\begingroup$ Thanks guys! This is helpful. $\endgroup$ – echo Dec 31 '17 at 0:22

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