Školjka There are six ports on a lake. Is it possible to organize a series of routes satisfying the following conditions ?
(i) Every route includes exactly three ports;
(ii) No two routes contain the same three ports;
(iii) The series offers exactly two routes to each tourist who desires to visit two different arbitrary ports.
(i) Every route includes exactly three ports;
(ii) No two routes contain the same three ports;
(iii) The series offers exactly two routes to each tourist who desires to visit two different arbitrary ports.