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authorNorbert Preining <norbert@preining.info>2019-09-02 13:46:59 +0900
committerNorbert Preining <norbert@preining.info>2019-09-02 13:46:59 +0900
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+Date: 15 Sep 1993 16:34:45 -0400 (EDT)
+From: Michael Downes <MJD@MATH.AMS.ORG>
+Subject: Around the Bend #11
+To: info-tex@shsu.edu
+X-ListName: TeX-Related Network Discussion List <INFO-TeX@SHSU.edu>
+
+The answer to Exercise 10, posted a couple of days ago, noted the
+unsatisfactory fourfold bloating of the encoded text. This leads to
+Exercise 11, which is rather difficult (double-dangerous bend level).
+
+************************************************************************
+*** Exercise 11 (hard):
+Write your own decoder to solve the problem I set for myself in
+Exercise 10: Using as few lines of TeX code as possible, set up an
+Around the Bend post containing a typical exercise so that it can be
+processed by plain TeX to (a) skip over the exercise text and (b)
+decode an embedded encoded answer. Come up with a better encoding idea
+than my previous one, that doesn't increase the size of the text by
+300% during encoding.
+
+************************************************************************
+
+Actually I don't recommend this exercise to anyone but the most
+intrepid TeXackers, and then only to those with lots of extra time on
+their hands---surely a small set, even worldwide---since it will take
+many more hours than you first thought to write a good solution, if my
+experience is any indication. Issuing the problem now as an exercise
+is more to place it on record, since I'm working on it anyway, than to
+instigate serious attempts at a solution by other people.
+
+The answer to Exercise 10 mentioned four design goals: (1) small
+decoder (2) minimum expansion of text during encoding (3) avoidance of
+special characters that tend to be corrupted by mailers or network
+gateways (4) supported character set ASCII 9,13,32--126 in the text to
+be encoded.
+
+However, in my ongoing efforts to wrassle with this problem, I have
+since decided to drop ASCII 9 [tab] from (4), and to eliminate (3),
+because it seems to be an independent issue: If mistranslated
+characters are a problem for the reader then they are a problem for
+the unencoded exercise text as well, and not just for the encoded
+answer. So now I am assuming that the reader has in hand a reliable
+copy of the posting with newlines and all visible ASCII 32---126
+accurately transmitted, and I am using basically a simple translation
+table for the encoding and decoding (beware: oversimplification).
+
+Since the text to be encoded will be under my control, I don't
+anticipate ever needing to include an actual tab character that cannot
+be converted to spaces or written in TeX notation as ^^I.
+
+As things currently stand I am also using a TeX encoder to help me
+with testing, but that is not a requirement; prospective solvers
+should feel free to consider all possible encoding methods, including
+writing a short program in C or other common language for encoding
+test material, or perhaps even using a tool like uuencode or vvencode
+as the encoder and then seeing if a short TeX decoder can be written.
+
+A summary of solutions, or more likely, `the' solution (mine), will be
+posted December 31, 1993. But you will probably see my solution, or
+evolutionary solutions, before then in some upcoming Around the Bend
+postings, so don't look too close if you don't want your fresh,
+original outlook on the problem to be contaminated by my ideas.
+
+If any readers do have difficulties with mistranslated characters in
+Around the Bend postings, I would like to hear the details. For
+checking, I give an ordered list of the ASCII characters 32--126
+below.
+
+Michael Downes %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+mjd@math.ams.org (Internet) ASCII 32--54,55--126: !"#$%&'()*+,-./0123456
+789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~