The following could help. We can take an expression by ex.

```
expr = (a && b && e && f) || (c && d && e && h);
```

and express it as an "exclusive sum of products".

```
BooleanConvert[expr, "ESOP"]
(* (c && d && e && h) ⊻ (a && b && e &&
f &&! h) a (a && b &&! d && e && f && h) ⊻ (a &&
b &&! c && d && e && f && h) *)
```

If you can calculate the probabilities of the individual terms, the probability of the expression should simply be the sum of these.