  This expository and review paper deals with the Diamond Lemma for ring
theory, which is proved in the first section of G. M. Bergman, The Diamond
Lemma for Ring Theory, Advances in Mathematics, 29 (1978), pp. 178-218. No
originality of the present note is claimed on the part of the author, except
for some suggestions and figures. Throughout this paper, I shall mostly use
Bergman's expressions in his paper. In Remarks and Notes, the reader will find
some useful information on this topic.
