21 Dec
2018
21 Dec
'18
5:11 p.m.
The usual arggh. Changed notation in midstream. << Let X denote the union of all H_n, n <= 0, and all C_n, n > 0. should read ----- Let X denote the union of all X_n, n <= 0, and all X_n, n > 0. ----- Sorry about that. —Dan