Symbol for Mutual Inclusive events is there any symbol for mutual inclusive(opposite of Mutually exclusive) events in probability. I meant to say is for OR we have `U` symbol in Set Theory. Likewise is there any symbol for Mutual Inclusiveness.

You want to say that two events $A$ and $B$ satisfy

1. If $A$, then $B$;
2. If $B$, then $A$.



That is, $A$ if and only if $B$. Thus $A$ and $B$ are mutually inclusive if and only if $A$ and $B$ happen simultaneously. We might say that $A$ and $B$ are _equivaent events_ , or that $A$ and $B$ are _concurrent events._ (I don't think either notation is standard.)

Symbolically, I suppose you'd want to use $A \equiv B$ or $A=B$ (denoting the fact that mutual inclusion is an equivalence relation). I don't think any particular form is standard.