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Published online by Cambridge University Press: 20 January 2009
Sr denotes an infinite space of r dimensions. Such a space is divided into two regions by a Sr−1. An infinite line is divided into n + 1 regions by n points. An infinite plane or other surface topically equivalent to it is divided into two regions by an infinite line.
* Cayley, (Mess. Math., IV, p. 167)Google Scholar gives this formula in the form ½(n 2+n+2), and the corresponding formula for φ3(n), ½(n 2+5n + 6).
* A particular case of this Theorem, viz., φn(n + l) = 2n + 1 − 1 is given in Schoute's, Mehrdimensionale Geometric, II (Leipzig 1905), 6.Google Scholar