Thus if we know about one thing is true, and also we know that a sentence when there thing is in a disjunction is true. Here if we consider example, like we see that "Tony Blair is prime minister" is true. So from this we can justify and infer any disjunction as long as we include this true sentence as a disjunct. Thus we can infer that "Tony Blair is prime minister or the moon is made of blue cheese", that makes perfect sense.
Ai/( A1? A2? ... ? An)
Once again, 1 ≤ i ≤ n.