ERRATA IN "The Way of Z", 1st printing

** Chapter 5 **

36, 2nd paragraph from bottom: "... < a <= ..." means

(iroot(a) - 1)*(iroot(a) - 1) < a <= iroot(a)*iroot(a)

Thanks to CJ Biazak for pointing this out.
 
** Chapter 9 **

78, 3rd line from the bottom: "(9, 11, 1989)" (second occurence)
should be "(11, 9, 1989)" (different from first occurence).

p. 90, Elevator example: Text says "first three elevators are stopped
at the first floor" but Z says {1->3, 2->1, 3->1, 5->7, ...}.  It
should be {1->1, 2->1, 3->1, 5->7, ...}

** Chapter 10 **

111, Exercise 10.8.1: "What is the meaning of this predicate ..."
should be "What is the truth value of this predicate ..."

** Chapter 12 **

133, "Factor expresses that two numbers n and d are factors of n"
should be "... two numbers q and d ... "

136, footnote 3 on negations says x \in S <==> \lnot (x \in S).
It should be x \notin S <==> \lnot (x \in S). 

** Chapter 15 **

154, Exercise 15.2.1: "2*x + 7 = 13 <=> x = 3" should be " ... => ... "
(equivalence symbol "<=>" should be implication symbol "=>")

157,  Last formula: size operator # in wrong place, 

   #ch? e printing /\ ((left^<ch?>)^right) <= maxsize

should be 

   ch? e printing /\ #((left^<ch?>)^right) <= maxsize
  
** Chapter 18 **

174: The fifth queen is missing from the set display.

  { 1 -> 8, 2 |-> 4, 3 |-> 1, 4 |-> 3, 6 |-> 2, 7 |-> 7, 8 |-> 5 }

It should be:

  { 1 -> 8, 2 |-> 4, 3 |-> 1, 4 |-> 3, 5 |-> 6, 6 |-> 2, 7 |-> 7, 8 |-> 5 }

176: The formulas for up and down are wrong.  In all the squares on
the left edge of the board (Fig 18.2) the up and down diagonal are
both the same as the rank, but in these squares the file is 1 not 0.
Change the equation of a line to:

  rank = slope x (file - 1) + intercept

where slope = 1 where intercept = up and slope = -1 where intercept = down.

Change the two formulas to:

  up = rank - (file - 1) = rank - file + 1
  down = rank + (file - 1) = rank + file - 1

DIAGONAL ranges from the smallest possible value for up which is 1 - SIZE + 1 
to the largest possible value for down which is SIZE + SIZE - 1 so change
the next formula to 

  DIAGONAL == -SIZE .. 2*SIZE - 1

Then in the axiomatic definition change to

  up(f,r) = r - f + 1 
  down(f,r) = r + f - 1

178: Change the formulas to be consistent with the corrections above:

  DIAGONAL == -SIZE .. 2*SIZE - 1

  up(f,r) = r - f + 1 
  down(f,r) = r + f - 1

** Chapter 21 **

208, NewSetting schema: "actual' = actual" should be "measured' = measured"

** Chapter 24 **

p. 233, text  above TYPE ERROR, "the domain of error is Param" should be 
"the domain of offset is Param"

** Part IV, Further Reading (after Chapter 25) **

241, third paragraph: "Morgan[1990]" should be "Morgan[1994]".

** Chapter 27 **

255: Two of the comments in the C code example at the bottom of the
page are incorrect.  They do not agree with the code (the code itself
is correct).  The two incorrect lines are:

        term=term+2;   /* term = 2*i-1 */
        sum=sum+term;  /* sum  = 1 + 3 + 5 + ... + 2*i - 1 */

These should be:

        term=term+2;   /* term = 2*(i+1) + 1 */
        sum=sum+term;  /* sum  = 1 + 3 + 5 + ... + (2*(i+1) + 1) */

263: "... the refinement symbol $\subbageq$ plays much the same role
that equivalance does in ordinary proofs"  
should be  " ... that implication does ..."

** Chapter 28 **

269: PS schema: "output" should be "value" (two places) to
match prior definitions on pp. 221 & 222. Also in the C code.

270: In the C code: 

 #define N_BPLS = YWOB + 1 

should be 

 #define N_BPLS YWOB + 1 
 
(with no equal sign) 

** Appendix A, Glossary **

301, range restriction and antirestriction: arguments reversed,

  A |>  R   Range restriction
  A |>- R   Range antirestriction 

should be

  R |>  A   Range restriction
  R |>- A   Range antirestriction 

** Appendix D **

309: Declaration of nonmembership relation is missing.  Inside the
generic definition box, add this line:

	_ \notin _ : X <-> PX

(where \notin is the slash epsilon symbol and P is the power set symbol)

Declarations of union _U_, intersection, set difference _\_ are  wrong

  PX x PX -> X

should be 

  PX x PX -> PX

313: Declaration of prefix minus operator uses wrong symbol.  In the
third declaration in the axiomatic definition box,

	- : Z -> Z

change the initial character from a (small, narrow) hyphen to a
(wider) minus sign, and add a bit more space before the colon.

** Appendix E **

317: Contrapositive, text says p => q  <=>  ~p => ~q
It should be p => q  <=>  ~q => ~p

321: C conditional expression, text says if (p) x = y; else x = z 
It should be x = p ? y : z

** Appendix F **

323, Exercise 15.2.1: "divide both sides by three" should be "... by two",
"e div 3" should be "e div 2".

** Bibliography **

334: Kalet, et al. (1996) has appeared, Vol. 36, No. 2, pages 451 - 461.


Errors in grammar, spelling, formatting, etc.:

** Chapter 1 **

3, first line last paragraph: "appears on" should be "turns on"

8, fig. 1.1 caption: "D is does" should be "D is dose"

** Chapter 2 **

16, near bottom: "a entire" should be "an entire"

20: Separate second paragraph from preceding bulleted paragraph, add a
bit of vertical space before first sentence "I don't mean ..."

** Chapter 5 **

35, Next to last paragraph: "It tells use more." should be "It tells
us more."

** Chapter 6 **

40, paragraph 3, line 4: "on directly" should be "directly on"

** Chapter 10 **

100, sec. 10.4.1, par. 3: "the the" should be "the"

** Chapter 12 **

134: Two exercises are unnumbered

136, near top: "Explanding" should be "Expanding"

** Chapter 15 **

155, line 8 under section 15.4 "We can can calculate..." should be
     "We can calculate ..."

** Chapter 28 **

278: Exercise 23.8.1 should be numbered 28.3.8.1

296, second line under Conclusion: "A Z formula" should be "a Z formula".

** Index **

340: "antecedent" is a top-level entry; it should not be indented
under "ANSI".

A current version of this document is kept at 
 http://staff.washington.edu/~jon/z-book/errata-1.txt

Thanks to all who have reported errors.  

Please report any others to jon@u.washington.edu
 
Last revised  20-Dec-2007