While trying to understand the relation between AdaBoost and Forward Stagewise Additive Modeling, I came across the following notation:
$$ G_m = arg \min_{b \in H} \sum_{i=1}^n w_i^{(t)} I_{y_i \neq b(x_i)} $$
I do not understand what $$ I_{y_i \neq b(x_i)} $$ looks like. Is it a square matrix with ones on the diagonal except where $y_i = b(x_i)$?
I hope someone who has seen this notation before can explain this. Thanks in advance.
Found it. It's the indicator function.