the place_of_birth of john is sydney;
the place_of_birth of mary is sydney;
the location of sydney is australia;
the belonging_adjective of australia is australian;

rule nationality
	if	the place_of_birth of Person is City and
		the location of City is Country and
		the belonging_adjective of Country is Adjective
	then	the nationality of Person is Adjective;

askable place_of_birth 'where was this person born? ';