The elementary relation in a decision diagram is equality between a variable and a value in its domain, for example
i == 5.
Normally, there is more than one variable, and relations use combined equalities through conjunction (the
and operator) and disjunction (the
X ::= (i == 5 and j == 1) or (i == 2 and j == 1)
The example shows a relation named
X that holds when
j is equal to
i must be either
The library itself provides constant relations
ONE to express
true (the relation that always holds), and
ZERO to express
false (the relation that never holds).