EDB — 24Y

[24Y]Note that there are 9 cases, 3 for the LHS and 3 for the RHS. We concord that \(∞,-∞\) are symbols and not elements of \(X\); if \(X\) has a maximum \(m\) then the intervals are preferably written as \((x,∞)=(x,m]\) and \([x,∞)=[x,m]\); similarly if \(X\) has a minimum.