It is well known that the monoid ring of the free product of a free group and a free monoid over a skew field is a fir. We give a proof of this fact that is more direct than the proof in the literature.
@article{urn:eudml:doc:41126,
title = {Monoid rings that are firs.},
journal = {Publicacions Matem\`atiques},
volume = {34},
year = {1990},
pages = {217-221},
zbl = {0706.16019},
language = {en},
url = {http://dml.mathdoc.fr/item/urn:eudml:doc:41126}
}
Pitarch, Andreu. Monoid rings that are firs.. Publicacions Matemàtiques, Tome 34 (1990) pp. 217-221. http://gdmltest.u-ga.fr/item/urn:eudml:doc:41126/