% CHANGES TO VOLUME 1 OF THE ART OF COMPUTER PROGRAMMING
%
% Copyright (C) 2022 by Donald E. Knuth
% This file may be freely copied provided that no modifications are made.
% All other rights are reserved.
%
% Three levels of changes to the books are distinguished here:
%
% "\bugonpage" introduces the correction of an error;
% "\amendpage" introduces new material for future editions;
% "\improvepage" introduces ameliorations of lesser importance.
%
% (Changes introduced by \improvepage do not appear in the hardcopy listing.)
%
% Also, "\planforpage" introduces some of the author's half-baked intentions.
%

% NOTE: TO PUT THE INDEX ON A SEPARATE PAGE, RUN THIS WITH THE COMMAND LINE
%   tex "\let\indexeject+ \input err1"

\newif\ifall % \alltrue means show the trivial items too
\relax % hook

\def\vertical{|}
\def\inref#1 #{\expandafter\def\csname\vertical#1\endcsname}
\catcode`|=\active
\let|\inref \input \jobname.ref
\catcode`|=12

\input taocpmac % use the format for TAOCP, with modifications below

\def\becomes{\ifmmode\ \hbox\fi{\manfnt y}\ } % wiggly arrow indicates a change

\def\bugonpage#1.#2 #3 (#4) {
  \medbreak\defaultpointsize
  \line{\kern-5pt\llap{\manfnt x}% print a black triangle in left margin
   {\bf Page #2}\enspace #3
   \leaders\hrule\hfill\ \eightrm\date#4.}
  \nobreak\smallskip\iftrue\noindent}
\def\amendpage#1.#2 #3 (#4) {
  \medbreak\defaultpointsize
  \line{\kern-5pt{\bf Page #2}\enspace #3
   \leaders\hrule\hfill\ \eightrm\date#4.}
  \nobreak\smallskip\iftrue\noindent}
\def\improvepage#1.#2 #3 (#4) {\ifall
  \medbreak\ninepoint
  \line{\kern-6pt{\sl Page #2\enspace #3\/}
   \leaders\hrule\hfill\ \eightrm\date#4.}
  \nobreak\smallskip\noindent}
\def\planforpage#1.#2 #3 (#4) {
  \medbreak\defaultpointsize
  \line{\kern-5pt{\bf Page #2}\enspace #3
   \leaders\hbox to 5pt{\hss.\hss}\hfill\ \eightrm\date#4.}
  \nobreak\smallskip\begingroup\let\endchange=\endgroup\sl\noindent}
\let\endchange=\fi
\def\nl{\par\noindent}
\def\nlh{\par\noindent\hangit}
\def\hangit{\hangindent2em}
\def\cutpar{{\parfillskip=0pt\par}}

\def\date#1.#2.#3.{% convert "yy.mm.dd." to "dd Mon 19yy"
  #3
  \ifcase#2\or Jan\or Feb\or Mar\or Apr\or May\or Jun\or
               Jul\or Aug\or Sep\or Oct\or Nov\or Dec\fi
  \ \ifnum #1<97 \hundred#1\else19#1\fi}
\def\hundred{20} % the "century" for dates before '97

\def\ex #1. [#2]{\ninepoint
  \textindent{\bf#1.}[{\it#2\/}]\kern6pt}
\def\EX #1. [#2]{\ninepoint
  \textindent{\llap{\manfnt x}\bf#1.}[{\it#2\/}]\kern6pt}

\def\foottext#1{\medskip
        \hrule height\ruleht width5pc \kern-\ruleht \kern3pt \eightpoint
        \smallskip\textindent{#1}}
\def\volheadline#1{\line{\cleaders\hbox{\raise3pt\hbox{\manfnt\char'36}}\hfill
       \titlefont\ #1\ \cleaders\hbox{\raise3pt\hbox{\manfnt\char'36}}\hfill}}
\def\refin#1 {\let|\inref \input #1.ref \let|\crossref}

\let\defaultpointsize=\tenpoint

%%%%%%%%%%%%%% opening remarks %%%%%%%%%%%%%%%%%%%%%%%%

\def\lhead{INTRODUCTION}
\let\rhead=\lhead
\titlepage
\volheadline{THE ART OF COMPUTER PROGRAMMING}
\bigskip
\volheadline{ERRATA TO VOLUME 1 (after 2021)}
\bigskip

\noindent This document is a transcript of the notes that I have been making
in my personal copy of {\sl The Art of Computer Programming}, Volume~1 (third
edition, 27th printing), since it was first printed in 2022.
Previous errata are recorded in another file `{\tt all1-pre.ps}'.

\ifall Four levels of updates\dash---``errors,'' ``amendments,'' ``plans,''
   and ``improvements''\dash---appear, indicated by four
\else Three levels of updates\dash---``errors,'' ``amendments,'' and
   ``plans''\dash---appear, indicated by three \fi
different typographic conventions:
\begingroup\def\hundred{17}

\bugonpage 0.666 line 1 (76.07.04)
Technical or typographical errors (aka bugs) are the most critical items, so
they are flagged with a `\thinspace{\manfnt x}\thinspace' preceding the page
number. The date on which I first was told about the bug is shown; this is the
effective date on which I paid the finder's fee. The necessary
corrections are indicated in
a straightforward way. If,~for example, the book says
`$n$' where it should have said `$n+1$', the change is shown thus:
\smallskip
$n$ \becomes $n+1$
\endchange

\amendpage 0.666 line 2 (89.07.14)
Amendments to the text appear in the same format as bugs, but without
the~`\thinspace{\manfnt x}\thinspace'. These are things I wish I had known
about or thought of when I wrote the original text, so I added them later.
The date is the date I drafted the new text.
\endchange

\def\hundred{19}

\planforpage 0.666 line 3 (17.11.20)
Plans for the future represent a third kind of item. In such notes I~sketched
my intentions about things that I wasn't ready to flesh out further when
I~wrote them down. You can identify these items because they're written in
slanted type, and preceded by a bunch of dots
`\hbox to 6em{\leaders\hbox to 5pt{\hss.\hss}\hfill}' leading to the date on
which I recorded the plan in my files.
\endchange

\improvepage 0.666 line 4 (38.01.10)
The fourth and final category\dash---indicated by page and line number in
smaller, slanted type\dash---consists of minor corrections or improvements
that most readers don't want to know about, because they are so trivial.
You wouldn't even
be seeing these items if you hadn't specifically chosen to print the complete
errata list in all its gory details.
Are you sure you wanted to do that?
\endchange

\endgroup
\ifall\else\medskip\ninepoint
My personal file of updates also includes a fourth category of items, not
shown in this list. They are miscellaneous minor corrections or improvements
that most readers don't want to know about, because they are so trivial.
If you really want to see all of the gory details,
you can download the full list from Internet webpage
$$\.{http://www-cs-faculty.stanford.edu/\char`\~knuth/taocp.html}$$
by selecting the ``long form'' of the errata.
\fi

\medskip
\tenpoint
My shelves at home are
bursting with preprints and reprints of significant research results that I
want to digest and summarize, where appropriate, in the ultimate edition of
Volume~1. I didn't do that in the third edition because I would surely have to do
it over again later: New results continue to pour forth at a great rate, and I
will have time to rewrite that volume only~once. Volumes 4 and~5 need to be
finished first. So I've put most of my effort so far into writing up
those parts of the total picture that seem to have converged to their
near-final form. It follows, somewhat paradoxically, that the updates in this
document are most current in the areas where there has been least activity.

On the other hand I do believe that the changes listed here bring Volume~1
completely up to date in two respects: (1)~All of the research problems in the
previous edition\dash---i.e., all exercises that were rated 46 and
above\dash---have received new ratings of 45 or less whenever I learned of a
solution; and in such cases, the answer now refers to that solution.
(2)~All of the historical information about pioneering developments has been
amended whenever new details have come to my attention.

\beginconstruction
The ultimate, glorious, 100\% perfect editions of Volumes 1--4 are works in progress.
Please let me know of any improvements that you think I ought to make.
Send your comments either by snail mail to D.~E. Knuth, Computer
Science, Gates Building 1B, Stanford University, Stanford CA~94305-9015,
or by email to
{\tt taocp{\char`\@}cs.stanford.edu}. (Use email for book suggestions
only, please\dash---all
other correspondence is returned unread to the sender, or discarded,
because I have no time to
read ordinary email.) Although I'm working full time on
Volume~4 these days, I~will try to reply to all such messages
within a year of receipt. Current news about {\sl The Art of Computer
Programming\/} is posted on
$$\.{http://www-cs-faculty.stanford.edu/\char`~knuth/taocp.html}$$
and updated regularly.
\par\endconstruction
\rightline{\dash---Don Knuth, January 2011}

\bigskip
\bigskip
{\quoteformat
What happened?
The subject took the bit in its teeth and ran away with it,
that's what happened.
I know now how Sir James Frazer felt when,
after setting out to dash off a brief monograph
on a single obscure rite, he found himself
in the embarrassing possession of
the 12 volumes of ``The Golden Bough.''
\author WAVERLEY ROOT (1974)
% International Herald Tribune, 22 May 1974, p8
\bigskip
No matter how many times you proofread your book,
after publication there will be roughly one typo per page.
\author JOSEPH H. SILVERMAN (2017)
% "A tale of two books", Bull AMS 54 (2017), 593
\vfill\eject
}

\def\today{\number\day\space\ifcase\month\or
  January\or February\or March\or April\or May\or June\or
  July\or August\or September\or October\or November\or December\fi
  \space\number\year}

%%%%%%%%%%%%%%% CHANGES FOR VOLUME 1 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\def\lhead{CHANGES TO VOLUME 1: FUNDAMENTAL ALGORITHMS}
\let\rhead=\lhead
\titlepage
\volheadline{FUNDAMENTAL ALGORITHMS}
\bigskip
\rightline{Copyright \copyright\ 2022
 Addison\with Wesley}
\rightline{Last updated \today}
\bigskip
%\rightline{\sl Most of these corrections have already been made in
%                  recent printings.}
\smallskip
\let\defaultpointsize=\tenpoint

\improvepage 1.16 line 18 (22.02.18)
the key inductive assertions. Those assertions either \becomes
the key assertions. Those asserions\dash---which are often called
``inductive assertions'' because we prove them by induction on the
length of computation\dash---either
\endchange

\amendpage 1.27 line 5 (22.03.01)
following equivalent \becomes following essentially equivalent
\endchange

\bugonpage 1.63 line $-10$ (22.08.11)
$\displaystyle \sum_k$ \becomes $\displaystyle \sum_{k\ge0}$
\endchange

\bugonpage 1.63 lines $-3$ and $-2$ (22.08.11)
$\displaystyle \sum_n$ \becomes $\displaystyle \sum_{n\ge0}$
\endchange

\bugonpage 1.70 append a new line to exercise 25 (22.08.09)
\ninepoint\noindent
where again the left-hand side is considered to be a polynomial in $r$.\nl
[Also change `.' to `,' on the preceding line.]
\endchange

\amendpage 1.77 the line before {\eq(10)} (22.03.01)
$S_1=x$ \becomes $S_0=0$
\endchange

\amendpage 1.77 line $-7$ (22.03.01)
{\sl If $x>0$, then\/} \becomes
{\sl If $x>0$ and $n\ge0$, then}
\endchange

\amendpage 1.79 new exercise for Section 1.2.7 (13.02.11)
\ninepoint
\ex25. [M21] Let $H_n^{(u,v)}=\sum_{1\le j\le k\le n}1/(j^uk^v)$.
What are $H_n^{(0,v)}$ and $H_n^{(u,0)}$?
Prove the general identity
$H_n^{(u,v)}+H_n^{(v,u)}=H_n^{(u)}H_n^{(v)}+H_n^{(u+v)}$.
\endchange

\bugonpage 1.80 third paragraph, line 4 (22.04.06)
not greater than $F_k$, \becomes
not greater than $F_k$, and $k>1$,
\endchange

\amendpage 1.83 replacement for {\eq(13)} (22.08.07)
\noindent
$$\phihat =1-\phi =-1/\phi={\textstyle\half }(1-\sqrt{5}\,).\eqno(13)$$
\endchange

\bugonpage 1.85 in exercises 22 and 23 (22.04.06)
\ninepoint number. \becomes number when $n\ge0$.\nl
[And exercise 25 should also specify that $n\ge0$.]
\endchange

\bugonpage 1.86 in exercise 31 (22.04.06)
\ninepoint $\phi^{-2n-1}\!@$. \becomes
$\phi^{-2n-1}\!@$, when $n\ge0$.
\endchange

\amendpage 1.88 line $-10$ (22.08.09)
simplest example \becomes simplest nontrivial example
\endchange

\let\defaultpointsize=\ninepoint % get ready for answer pages

\amendpage 1.471 append a new paragraph to answer 1 (22.03.01)
\em Note: We might also say that $a_2+\cdots+a_0=\sum_{j=2}^0a_j$, and that
$\sum_{j=p}^q a_j+\sum_{j=q+1}^r a_j=\sum_{j=p}^r a_j$, using the left
half of~\eq(1). On the other hand, we should {\it not\/} replace $\cdots$ using
the right half of~\eq(1)! The sum $\sum_{2\le j\le 0}a_j$ is~0, by~\eq(2).
\endchange

\amendpage 1.472 new copy for end of answer 30 (22.07.01)
exercise~46.) \becomes
exercise~46. Cauchy's sums were extended to integrals by
V.~Bouniakowsky [{\sl M\'em.\ Acad.\ St.-P\'etersbourg\/ \rm(7) \bf1}
(1859), No.~9, 4] % page 4 of 18
and H.~A. Schwarz [{\sl Acta Societatis Scientiarum Fennic\ae\/ \bf15} (1885),
315--362].)
\endchange

\bugonpage 1.492 replacement for answer 9 (22.03.01)
\ans9.  $(n=0?\ 0{:}\ {-1}/n)$.
\endchange

\amendpage 1.493 new answer for section 1.2.7 (22.03.01)
\ans25. $H_n^{(0,v)}=\sum_{k=1}^n k^{1-v}=H_n^{(v-1)}$
and $H_n^{(u,0)}=\sum_{k=1}^n H_k^{(u)}$;
so the identity generalizes~\eq(8). [See L.~Euler,
{\sl Novi Comment.\ Acad.\ Sci.\ Pet.\ \bf 20} (1775), 140--186, \S2.]
\endchange

\expandafter\ifx\csname indexeject\endcsname\relax\else\vfill\eject\fi
\amendpage 1.630 and following (22.02.01)
Miscellaneous changes to the existing index of Volume~1 are collected here,
including corrections and amendments to the old entries as well as new entries
that are occasioned by the new material. Thus, the lines of the full index
that have changed serve also as an index to the present document. However,
when a correction or amendment has caused an old index entry to be deleted,
the deletion is usually not indicated.

\input exotic
\begindoublecolumns
\indexformat
\gdef\Uni1.08:{\bitmap24:1.08:}
\hangindent 2em
Bouniakowsky, Viktor Iakowlewitch  ({\rus Bunyakovski1i0, Viktorp2 Yakovlevichp2}), 472. % 51st
Schwarz, Karl Hermann Amandus, inequality, 36, 472. % 51st
Strongly zero, 57. % 51st

\vfill
\enddoublecolumns
\endchange

\bye

[The next printing will be the 51st.]
[Due to publisher error, the 50th printing was identical to the 49th.]
Not mentioned above:
the change to page 16 affects page 15
page 86, improved wording of exercise 38
Page 108 had extra left paren in (10)
Page 159, added vdots and ddots into the matrices
I deleted "Reading, Mass" from page 471 line 4
Page 472 had Khar,kov not Khar'kov (corrected 02 July 2022 in 1.2.3.tex)

ARTICLES "TO APPEAR" THAT ARE STILL PENDING:

FIX the line about "almost all changes..." when the 51st printing comes out