Errata for Knowledge Representation

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.

Dust Jacket

Back cover, Line 2: Replace "own concept of frames" with "conceptual graphs".

Back cover, Highlights: Replace "CLIP" with "CLIPS".

1. Logic

1.1 Historical Background   1

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.

1.2 Representing Knowledge in Logic   11

1.3 Varieties of Logic   18

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".

1.4 Names, Types, and Measures   29

Page 34: The symbol "^" preceding the concept [ [Gentleman: #16432] ] should be replaced with "¬".

1.5 Unity Amidst Diversity   39

Page 47, Exercise 22: Replace "page 000" with "page 9".

2. Ontology

2.1 Ontological Categories   51

2.2 Philosophical Background   55

2.3 Top-Level Categories   67

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.

2.4 Describing Physical Entities   78

Page 87, Figure 2.11: The category Part should have three subtypes, Piece, Participant, and Stage. Stage has been omitted.

2.5 Defining Abstractions   89

Page 95, Figure 2.14: The category Meterology should be Mereology.

2.6 Sets, Collections, Types, and Categories   97

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.

2.7 Space and Time   109

Page 124, Exercise #3: The reference should be to section 2.4 instead of 2.3.

3. Knowledge Representations

3.1 Knowledge Engineering   132

3.2 Representing Structure in Frames   143

3.3 Rules and Data   156

Page 164: Replace four occurrences of "ê" with "¬"

3.4 Object-Oriented Systems   169

3.5 Natural Language Semantics   178

3.6 Levels of Representation   186

4. Processes

4.1 Times, Events, and Situations   206

4.2 Classification of Processes   213

4.3 Procedures, Processes, and Histories   217

4.4 Concurrent Processes   223

4.5 Computation   232

4.6 Constraint Satisfaction   239

4.7 Change   245

5. Purposes, Contexts, and Agents

5.1 Purpose   265

5.2 Syntax of Contexts   274

5.3 Semantics of Contexts   284

5.4 First-Order Reasoning in Contexts   297

Page 302, definition of disjunction: Erase the letter "I" in the expression (~Iq) and print the letter "q" in italics.

5.5 Modal Reasoning in Contexts   307

Page 318: Replace the symbol "&scriptd" with a capital "D" in a script font.

5.6 Encapsulating Objects in Contexts   321

5.7 Agents   330

6. Knowledge Soup

6.1 Vagueness, Uncertainty, Randomness, and Ignorance   348

6.2 Limitations of Logic   356

6.3 Fuzzy Logic   364

6.4 Nonmonotonic Logic   373

6.5 Theories, Models, and the World   383

6.6 Semiotics   394

7. Knowledge Acquisition and Sharing

7.1 Sharing Ontologies   408

7.2 Conceptual Schema   417

7.3 Accommodating Multiple Paradigms   427

7.4 Relating Different Knowledge Representations   438

7.5 Language Patterns   445

7.6 Tools for Knowledge Acquisition   452

Appendix A: Summary of Notations

A.1 Predicate Calculus   467

Page 468: The definition of in terms of ~ and should be (~p)q.

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.

A.2 Conceptual Graphs   476

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".

A.3 Knowledge Interchange Format   489

Appendix B: Ontology Base

B.1 Principles of Ontology   492

B.2 Top-Level Categories   497

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.

B.3 Role and Relation Types   502

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".

B.4 Thematic Roles   506

B.5 Placement of the Thematic Roles   510

Appendix C: Extended Examples

C.1 Hotel Reservation System   513

C.2 Library Database   515

C.3 ACE Vocabulary   518

C.4 Translating ACE to Logic   518

Answers to Selected Exercises


Name Index

Subject Index

For more information, see the index and the preface of the book.

Please send comments and error reports to John F. Sowa.


Thanks to the following people for reporting some of these errors and typos: Susan Bridges and her students, and Rob Harrap.

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