confuse of required and prohibited in BooleanQuery
I'm confused by the two argument "required" and "prohibited" in
public void add(Query query, boolean required, boolean prohibited)
There are two statement in "Lucene in Action"
1. Performing an OR query only requires setting the required and
prohibited flags both to false
2.There are four logical combinations of these flags, but the case where
both are true is an illogical and invalid combination
but I don't know why, Can anybody explain it to me?