The middle levels conjecture (Havel 1983, Buck and Wiedemann 1984), also known as revolving door conjecture, posits that the middle layer graph of order n has a Hamilton cycle for every n>=1. The conjecture was proved by Mütze; see also Mütze. Since the middle layer graphs are vertex-transitive, proving the conjecture established that these graphs are not counterexamples to Thomassen's conjecture on nonhamiltonian vertex-transitive graphs. Knuth gave the middle levels conjecture the highest difficulty rating (49/50) among all open problems in his book.
We guarantee you’ll find the right tutor, or we’ll cover the first hour of your lesson.
Club Z! has connected me with a tutor through their online platform! This was exactly the one-on-one attention I needed for my math exam. I was very pleased with the sessions and ClubZ’s online tutoring interface.
My son was suffering from low confidence in his educational abilities. I was in need of help and quick. Club Z! assigned Charlotte (our tutor) and we love her! My son’s grades went from D’s to A’s and B’s.
I’ve been using Club Z’s online classrooms to receive some help and tutoring for 2 of my college classes. I must say that I am very impressed by the functionality and ease of use of their online App. Working online with my tutor has been a piece of cake. Thanks Z.
Jonathan is doing really well in all of his classes this semester, 5 A’s & 2 B’s (he has a computer essentials class instead of PLC). In his Algebra class that Nathan is helping him with he has an A+.
Sarah is very positive, enthusiastic and encourages my daughter to do better each time she comes. My daughter’s grade has improved, we are very grateful for Sarah and that she is tutoring our daughter. Way to go ClubZ!
