<sentence> <Implies> <if> <Exists> <declare><Var>Ename</Var></declare> <declare><Var>Esalary</Var></declare> <formula> <And></And> </formula> </Exists> </if> <then> <Atom> <op><Const type="rif:iri">op:assert</Const></op> <arg><Var>ename</Var></arg> <arg><Var>esalary</Var></arg> </Atom> </then> </Implies> </sentence>