\input basic
\parskip 12 pt
\parindent 0 pt
\magnify {1100}
\ctrline{\bf CS154 PROBLEM SET 4, ERRATA}
The solution to 3.26 was incorrect.  It was pointed out that strings
that consist solely of $0$'s must occur in separate equivalence classes
from strings with some $0$'s followed by some positive number of $1$'s.
The correct solution appears in the notes on prefix- and infix-equivalence.

The gsm for I(a) maps the set of all Pascal programs onto the set of strings
of the form $a↑{n}b↑{n}$, instead of the set of strings of the form
$0↑{n}1↑{n}$.  This is no big deal.

\vfill\eject\end