The notion of free group is defined, a relatively wide collection of groups which enable infinite set summation (called {\bf commutative $\pi$-group}), is introduced. Commutative $\pi$-groups are studied from the set-theoretical point of view and from the point of view of free groups. Commutativity of the operator which is a special kind of inverse limit and factorization, is proved. Tensor product is defined, commutativity of direct product (also a free group construction and tensor product) with the special kind of inverse limit is proved. Some important examples of tensor product are computed.
@article{116944, author = {Jaroslav Guri\v can}, title = {Homology theory in the alternative set theory I. Algebraic preliminaries}, journal = {Commentationes Mathematicae Universitatis Carolinae}, volume = {32}, year = {1991}, pages = {75-93}, zbl = {0735.03032}, mrnumber = {1118291}, language = {en}, url = {http://dml.mathdoc.fr/item/116944} }
Guričan, Jaroslav. Homology theory in the alternative set theory I. Algebraic preliminaries. Commentationes Mathematicae Universitatis Carolinae, Tome 32 (1991) pp. 75-93. http://gdmltest.u-ga.fr/item/116944/
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