If three people have exactly one friend, then won't four people have the exact same friend X? Because if four people have a common friend, then the three people in that set of four that have a common friend also have a common friend, contradicting that they have exactly one common friend.
Kung ang tatlong tao ay may eksaktong isang kaibigan, At pagkatapos ay hindi apat na tao ay ang parehong kaibigan X? Dahil kung apat na tao ang isang pangkaraniwang kaibigan, Pagkatapos ng tatlong tao sa na-set ng apat na magkaroon ng isang karaniwang kaibigan mayroon ding isang pangkaraniwang kaibigan, Contradicting na sila mismo ang isa karaniwang kaibigan.