"every prime number is even" fails for n=3

@Carl-FredrikNybergBrodda an answer with these details would be beneficial for the history of the TSP; knowing about the people behind the progress seems important in its own right.

@P.R. that had already been noticed in the comments of Gerard Duchamp that was Kurrent and not Sütterlin

so the sum on right of Lemma 1 amounts to calculating the union of certain orthogaonal ranges via the inclusion-exclusion principle. I have apparently rediscovered that fact and could provide python code for that calculation. If it is considered appropriate I could add it to my question or provide it on request.

indeed a very helpful answer!

@Pedro di you have a reference for doing that in the multivariable case?

That's exactly what I was hoping for

@FedorPetrov yes, that is the problem the question is aimed at.

@RobPratt Hamiltonicitx doesn't apply and if we remove none of the vertices, we do not necessarly have a connected 2-regular graph