@@ -19,6 +19,7 @@ In the [previous sheet](../03_card_sat), we already used iterative model buildin
Linear expressions are algebraic formulas of the first degree, i.e., variables are not multiplied or divided by each other (or themselves).
As comparisons, only $\leq, =, \geq$ are allowed, but not true inequalities, making them essentially half-planes or spaces in a high-dimensional spaces (and the solution space linear).
An example for a linear constraint is $4\cdot x_1-3 \cdot x_2+0.5\cdot x_3 \geq 7.3$.
$x_1^2 \leq 3$ would *not* be linear as $x_1$ is multiplied by itself.
Advanced functions such as $\sin x$ are of course completely forbidden (though, there are tricks to approximate them).
