I'm working through an academic game theory paper and stumbled upon this summation notation in a proof and I'm not quite sure what it means:
$\sum\limits_{j \in M \backslash\ \{i\}}$
There is a set $M$ indexed by $j$. There are other terms in the expression indexed by $i$. I'm curious what the $\backslash\{i\}$ means. Does this mean "with the exception of $i$"?
This context is an actor ($i$)'s utility function that depends on what other actors in the set $M$ do. Other actors are indexed by $j$.