Trees of Homotopy Types of 2-Dimensional CW Complexes. II
Michael N. Dyer, Allan J. Sieradski · Transactions of the American Mathematical Society · 1975
A ir-complex is a finite, connected 2-dimensional CW complex with fundamental group 7r. The tree HT(r) of homotopy types of ircomplexes has width 6N if there is a root Y of the tree such that, for any ir-complex X, X V (VM1S2) lies on the stalk generated by Y. Let ir be a finite abelian group with torsion coefficients r1, * -, rn. The main theorem of this paper asserts that width HT(r) S n(n 1)/2. This generalizes the results of 141.