HumanitiesTextbook

forall x: Calgary

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forall x: Calgary introduces formal logic through precise languages, semantics and natural deduction. The hosted Fall 2025 edition, revised in September 2026, includes truth-functional, first-order and modal logic alongside advanced topics and reference material.

FormatPDF
LanguageEnglish
SubjectHumanities
LevelNot specified
No. of pages437
Published2025
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forall x: Calgary source edition coverFree

About this book

This open logic textbook develops from earlier versions of forallx and related materials, with contributions and revisions documented in its front matter. The reviewed preface explains entailment and satisfiability through both interpretation and formal deduction. Its nine-part organisation moves from informal logical ideas into truth-functional and first-order languages before extending the discussion. The instructor guidance describes a semester-long introductory route with optional selections. The hosted PDF’s revision identifier matters because the freely available source changes over time; courses should use consistent chapter and exercise references.

The attached edition contains 437 PDF pages, including front matter. Cover: source edition cover rendered from the PDF. The textbook and its original notices are retained; Academic Master’s study material is separate from the source text.

Book summary

Study overview of the reviewed opening

The preface introduces formal logic as the study of precisely defined languages and relationships between their sentences. Entailment concerns what must follow from assumptions; satisfiability concerns whether sentences can hold together without contradiction. These ideas can be studied through interpretations or through formal derivations.

The book first develops logical notions informally, then introduces truth-functional language. Its connectives combine sentences, allowing semantic methods such as truth tables and proof-theoretic methods such as natural deduction to be compared. First-order logic adds names, predicates, identity and quantifiers, making its language more expressive. The preface next identifies modal logic and advanced topics as extensions to that route.

The instructor guidance explains how selections can form a semester course and stresses the value of using one stable version. Appendices, a glossary and alternative notation discussions support reference use. The guide covers the preface and verified structure, not the individual proofs or exercise solutions. Students should match notation and rule names to this Calgary edition rather than importing conventions from another remix without checking them.

Book contents

  1. 1 Arguments
  2. 2 The scope of logic
  3. 3 Other logical notions
  4. 4 First steps to symbolization
  5. 5 Connectives
  6. 6 Sentences of TFL
  7. 7 Ambiguity
  8. 8 Use and mention
  9. 9 Characteristic truth tables
  10. 10 Truth-functional connectives
  11. 11 Complete truth tables
  12. 12 Semantic concepts
  13. 13 Limitations of TFL
  14. 14 Truth table shortcuts
  15. 15 Partial truth tables
  16. 16 The very idea of natural deduction
  17. 17 Basic rules for TFL
  18. 18 Constructing proofs
  19. 19 Additional rules for TFL
  20. 20 Proof-theoretic concepts
  21. 21 Derived rules
  22. 22 Soundness and completeness
  23. 23 Building blocks of FOL
  24. 24 Sentences with one quantifier
  25. 25 Multiple generality
  26. 26 Identity
  27. 27 Sentences of FOL
  28. 28 Definite descriptions
  29. 29 Ambiguity
  30. 30 Extensionality
  31. 31 Truth in FOL
  32. 32 Semantic concepts
  33. 33 Using interpretations
  34. 34 Reasoning about interpretations
  35. 35 Properties of relations
  36. 36 Basic rules for FOL
  37. 37 Proofs with quantifiers
  38. 38 Conversion of quantifiers
  39. 39 Rules for identity
  40. 40 Derived rules
  41. 41 Proofs and semantics
  42. 42 Introducing modal logic
  43. 43 Natural deduction for ML
  44. 44 Semantics for ML
  45. 45 Normal forms
  46. 46 Functional completeness
  47. 47 Proving equivalences
  48. 48 Soundness
  49. A Symbolic notation
  50. B Alternative proof systems
  51. C Quick reference
  52. Glossary

Questions for study

The following prompts are Academic Master’s editorial material.

  • How do entailment and satisfiability ask different questions?
  • What is the relationship between semantic and proof-theoretic methods?
  • Why should an entire class work from the same revision?

Sources and coverage

Preface read in full (PDF pages 7–10); title, licence, revision identifier and contents checked.

Source edition · Source licence

About access & copyright

Check this edition’s source and licence before reusing its files or content. A library listing does not grant additional rights.

Read our Library Access & Copyright policy

Logical relationships

Distinguish entailment from satisfiability.

Semantics and proof

Compare interpretations with formal derivations.

Increasing expressiveness

Identify the route into first-order and modal languages.

Stable references

Match exercises and notation to an edition.

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