- Aug 6, 2001I admire the book very much. Only one of the following is
unequivocally an "erratum," but hopefully at least one or two of the
others is worth considering.
p. 178, 6th bulletted point: "An inference process is complete if it
can derive all true conclusions from a set of premises." Wouldn't it
be better to say something like ". . . derive all the logical
consequences of a set of premises"? The "conclusion" of an invalid
argument might be true even though not a logical consequence of the
premises, and of course if one or more premises is false then there
will be false logical consequences that a complete process must be
able to derive. (Though the previous sentence does specify "true
p. 193, line 8: "The term well-formed formula or wff is sometimes
used for sentences that have all their variables properly introduced
[by quantifiers]." This is almost the opposite of the usage in e.g.
Barwise and Etchemendy, *Language, Proof, and Logic*. B&E
use "sentence" for a wff with all its variables bound by quantifiers!
On their usage, which I believe is pretty standard, "Brother(Richard,
x)" would be a wff but not a sentence.
p. 272, discussion of proof: should "Modus Ponens" be "Generalized
Modus Ponens"? Alternatively, there could be a note stating that
hereafter, "Modus Ponens" will be taken to mean "Generalized Modus
p. 278: some informal remarks about how to apply Generalized
Resolution would be very helpful.
pp. 663-4: "In programming languages, every statement is a
commmand." (a) perhaps this should be "in *procedural* programming
languages . . ."? (b) in any case, the phrase "every statement is a
command" could be puzzling, since this occurs in the context of a
discussion of speech acts, and in speech act theory "statement" is
often used for a kind of speech act distinct from commands,
p. 664, footnote 3, second sentence: first word should be "In",
p. 679, discussion of indexicals: ". . . which are interpreted as
fluents" -- as far as I can tell, this is the only use of the
term 'fluent' except for p. 241, where it is defined. Since that was
over 400 pages earlier, a cross reference or reminder of its meaning
would be helpful!