#### Volume 16, issue 6 (2016)

 Recent Issues
 The Journal About the Journal Editorial Board Editorial Interests Editorial Procedure Submission Guidelines Submission Page Subscriptions Author Index To Appear ISSN (electronic): 1472-2739 ISSN (print): 1472-2747
Loop near-rings and unique decompositions of H-spaces

### Damir Franetič and Petar Pavešić

Algebraic & Geometric Topology 16 (2016) 3563–3580
##### Abstract

For every H-space $X$, the set of homotopy classes $\left[X,X\right]$ possesses a natural algebraic structure of a loop near-ring. Albeit one cannot say much about general loop near-rings, it turns out that those that arise from H-spaces are sufficiently close to rings to have a viable Krull–Schmidt type decomposition theory, which is then reflected into decomposition results of H-spaces. In the paper, we develop the algebraic theory of local loop near-rings and derive an algebraic characterization of indecomposable and strongly indecomposable H-spaces. As a consequence, we obtain unique decomposition theorems for products of H-spaces. In particular, we are able to treat certain infinite products of H-spaces, thanks to a recent breakthrough in the Krull–Schmidt theory for infinite products. Finally, we show that indecomposable finite $p$–local H-spaces are automatically strongly indecomposable, which leads to an easy alternative proof of classical unique decomposition theorems of Wilkerson and Gray.

##### Keywords
H-space, near-ring, algebraic loop, idempotent, strongly indecomposable space, Krull-Schmidt-Remak-Azumaya theorem
Primary: 55P45
Secondary: 16Y30