This page lists errors and typos found in the first printing of the book Knowledge Representation by John F. Sowa. The error reports are displayed in red and grouped by chapter and section. Some passages, which are correctly printed but might be misinterpreted, are discussed in green.
Back cover, Line 2: Replace "own concept of frames" with "conceptual graphs".
Back cover, Highlights: Replace "CLIP" with "CLIPS".
Page 6, Figure 1.2: The letter "ß" on the lower right outside the circle should be erased.
Page 10, formula numbered 3 at the bottom of the page: The second capital pi should be replaced with a capital sigma.
Page 21: There is a missing open paren before the formula that represents the sentence of type A.
Page 23, Figure 1.8: The final "r" in the word "Trailer" is partly broken.
Page 27, axiom BF for the Barcan formula: erase the string ".br".
Page 34: The symbol "^" preceding the concept [ [Gentleman: #16432] ] should be replaced with "¬".
Page 47, Exercise 22: Replace "page 000" with "page 9".
Page 72, Figure 2.6, and page 498, Figure B.1: The categories Situation and Execution should be replaced with Structure and Situation, respectively. For the correct diagram, see the top-level ontology.
Page 87, Figure 2.11: The category Part should have three subtypes, Piece, Participant, and Stage. Stage has been omitted.
Page 95, Figure 2.14: The category Meterology should be Mereology.
Page 100, just below the middle of the page: The string ":ehp1" should be deleted, and the remainder of that line and the following line should be printed in Times Roman rather than italics.
Page 124, Exercise #3: The reference should be to section 2.4 instead of 2.3.
Page 164: Replace four occurrences of "ê" with "¬"
Page 302, definition of disjunction: Erase the letter "I" in the expression (~Iq) and print the letter "q" in italics.
Page 318: Replace the symbol "&scriptd" with a capital "D" in a script font.
Page 468: The definition of É in terms of ~ and Ú should be (~p)Úq.
Page 470, second sentence of the section titled "Formation Rules": Replace "notation of propositional logic" with "notation of predicate logic".
Page 475: In the Principia Mathematica, Whitehead and Russell used the symbols E! and E!! for relational operators. Kleene turned the E backwards for the quantifier $! meaning "there exists exactly one entity that meets the following conditions." Some authors call $! the unique existential quantifier. I prefer to call it the exactly-one quantifier and to reserve the adjective unique for the quantifier $!! meaning "there exists a unique entity that satisfies the following conditions for all possible values of the variables governed by the preceding universal quantifiers. As examples, see the representations of "exactly one mother" and "unique social security number" on Page 475.
Page 475: There is a missing parenthesis before the formulas that define the quantifiers for exactly one and unique.
Page 482: In the CG that shows the result of expanding the GoingTo relation, the arcs on the Agnt relation are reversed.
Page 487, Defintion A.2.10: The list should be numbered 1, 2, 3, 4.
Page 487: Delete ":" in the three occurrences of ":T".
Page 72, Figure 2.6, and page 498, Figure B.1: The categories Situation and Execution should be replaced with Structure and Situation, respectively. For the correct diagram, see the top-level ontology.
Page 502, Figure B.2: The category Participant should be changed to Part. Under Part, there should be three subtypes, Piece, Participant, and Stage. This diagram and Figure 2.11 on p. 87 should be identical, but as printed, they have different errors. The error in Figure 2.11 is a simple omission; the error in Figure B.2 is more serious.
Page 505, top line: The word "gneneral" should be "general".
For more information, see the index and the preface of the book.
Please send comments and error reports to John F. Sowa.
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