The Boolean domain {0, 1} can be replaced by the unit interval , in which case rather than only taking values 0 or 1, any value between and including 0 and 1 can be assumed. Algebraically, negation (NOT) is replaced with 1-x, conjunction (AND) is replaced with multiplication (xy), and disjunction (OR) is defined via De Morgan's law to be 1-(1-x)(1-y)=x+y-xy.
