Thus, the equations x=y and |''x''-=''y'' and <math>|x - y| = 0</math> are equivalent. Therefore the equations <math>|x - y| + |u - v| = 0</math> and <math>|x - y| \cdot |u - v| = 0</math> express the logical [[Logical conjunction|conjunction]] and [[disjunction]], respectively, of the equations ''x''=''y'' and ''u''=''v''. [[Negation]] can be expressed as <math>1 \dot - |x - y| = 0</math>.
