 As soon as one admits that truth values come with valuation systems, it is quite natural to assume that the elements of such a system are somehow interrelated. And indeed, already the valuation system for classical logic constitutes a well-known algebraic structure, namely the two-element Boolean algebra with \(\cap\) and \(\cup\) as meet and join operators (see the entry on the  mathematics of Boolean algebra).  In its turn, this Boolean algebra forms a lattice with a partial order defined by \(a\le_t b \textrm{ iff } a\cap b = a\). This lattice may be referred to as TWO. It is easy to see that the elements of TWO are ordered as follows: \(F\le_t T\). This ordering is sometimes called the truth order (as indicated by the corresponding subscript), for intuitively it expresses an increase in truth: \(F\) is “less true” than \(T\). It can be schematically presented by means of a so-called Hasse-diagram as in Figure 1.