On Wikipedia in the article Snell envelope author uses 'join' operation on random variables. Following line is relevant:
$$ U_n = X_n \lor \mathbb{E}^\mathbb{Q}[U_{n+1} | \mathcal F_n] \quad \text{for} \ \ n \neq N$$
Having read Wikipedia's definition it seems like it could be replaced by max. Is it a deliberately confusing notation or is there something to it?
$X\vee Y=\max(X,Y)$. Wikipedia is being obtuse by referring to $\vee$ as "join" when "max" is a clearer description.