MS 447-454 (1903) - Lowell Lecture I

26

we have a right to transform M into N in the graph just written, where it occurs under one hundred enclosures.

Therefore if Right No 1 holds good for disconnected graphs withing any even number of enclosures up to any number, it holds good also for the next higher even number of enclosures. But we have alreadyproved it for 0 and for 2 enclosures, and therefore it holds good for any even number of enclosures that can be reached by sucessive additions of 2.