TITLE: Notation: "$+$" exponent sign
QUESTION [9 upvotes]: I'm following this paper and came across some notation that I don't know; I've tried a number of queries such as "power to the plus", "plus exponent" etc but can't seem to find anything:
From page 4:
$\text{sign}(\beta_j)(|\beta_j| - \gamma)^+$
The "$+$" exponent is what I'm confused about.

REPLY [5 votes]: The notations $f^+$ and $f^-$ for (real valued) functions and constants denote what RGB hints at the positive and negative part, respectively.
In detail $f^+ = \max \{0, f\}$ and $f^- = - \min \{0, f \}$, so that $f = f^+ - f^-$. 
See the wikipedia page Positive and negative parts.