What does upside down "v" ($\wedge$) mean in this equation?
Solution 1:
$|x_i|\wedge t$ probably means $\min(|x_i|,t)$.
There are three usual meanings of the wedge ($\wedge$) symbol: logical conjunction, some sort of "wedge product" and the minimum function. As both $|x_i|$ and $t$ are scalars, we can rule out the first two possibilities. So the minimum function is the most plausible interpretation I can think of. But certainly, you should look at the context of your equation to make sure that this is a correct interpretation.