On the other hand, problems 1, 2, 5, 9, 15, 18, and 22 have solutions that have partial acceptance, but there exists some controversy as to whether they resolve the problems.
På den anden side har problemerne 1, 2, 5, 9, 15, 18, 21 og 22 løsninger, der er delvist accepteret, men hvor der hersker nogen strid om, hvorvidt problemet er fuldstændigt løst.