24.11.2017 Views

Abelian Groups - László Fuchs [Springer]

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

7 Solid Chains 557<br />

(4) A corank 1 solid subgroup of a B 1 -group is a B 1 -group.<br />

(5) Assuming CH, a corank 1 pure subgroup of a B 2 -group is a B 2 -group if and only<br />

if it is a solid subgroup.<br />

7 Solid Chains<br />

The solid exact sequences fail to form a proper class, consequently, they do not<br />

support a relative homological machinery. However, solid chains will provide us<br />

with powerful tools in the study of Butler groups of large cardinalities.<br />

Solid Chains Let A denote a pure subgroup of the torsion-free group G. Bya<br />

solid chain from A to G we understand a smooth chain<br />

A D G 0 < G 1

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!