champion(drobny).
champion(rosewall).
champion(goolagong).
champion(connors).
champion(borg).
champion(evert).

male(connors).
male(drobny).
male(rosewall).
male(borg).

female(kelly).
female(evert).
female(goolagong).

child(kelly,goolagong).

older(drobny,rosewall).              % Name1 is older than Name2
older(rosewall,goolagong).

born_before(borg,connors).           % Name1 was born before Name2
born_before(connors,kelly).
born_before(evert,connors).