Symbol x_0

Its job in the formula

$x_0$ is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.

Where the article explains it

For a system f , an input $x_0$ , a perturbation radius $\epsilon$ , and a safe output region S , the property being proved typically has the form $\forall$\, x $\in$ $B_\epsilon(x_0)$: $\quad$ f(x) $\in$ S, read as: for every input within radius $\epsilon$ of $x_0$ , the system’s output stays inside the safe region.

Learn the underlying idea

A subscript is a label attached below a symbol. It often selects a time step, component, category, or member of a sequence.

Open the illustrated subscripts: which member of a family? guide →