This monograph attempts to present the results known today on bases in
Banach spaces and some unsolved problems concerning them. Although this
important part of the theory of Banach spaces has been studied for more
than forty years by numerous mathematicians, the existing books on
functional analysis (e. g. M. M. Day [43], A. Wilansky [263], R. E.
Edwards [54]) contain only a few results on bases. A survey of the
theory of bases in Banach spaces, up to 1963, has been presented in the
expository papers [241], [242] and [243], which contain no proofs;
although in the meantime the theory has rapidly deve1oped, much of the
present monograph is based on those expository papers. Independently, a
useful bibliography of papers on bases, up to 1963, was compiled by B.
L. Sanders [219J. Due to the vastness of the field, the monograph is
divided into two volumes, ofwhich this is the first (see the tab1e of
contents). Some results and problems re1ated to those treated herein
have been de1iberately planned to be inc1uded in Volume 11, where they
will appear in their natural framework (see [242], [243]).