forall x: Calgary
Not rated yetRate this bookforall 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.
FreeAbout 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 Arguments
- 2 The scope of logic
- 3 Other logical notions
- 4 First steps to symbolization
- 5 Connectives
- 6 Sentences of TFL
- 7 Ambiguity
- 8 Use and mention
- 9 Characteristic truth tables
- 10 Truth-functional connectives
- 11 Complete truth tables
- 12 Semantic concepts
- 13 Limitations of TFL
- 14 Truth table shortcuts
- 15 Partial truth tables
- 16 The very idea of natural deduction
- 17 Basic rules for TFL
- 18 Constructing proofs
- 19 Additional rules for TFL
- 20 Proof-theoretic concepts
- 21 Derived rules
- 22 Soundness and completeness
- 23 Building blocks of FOL
- 24 Sentences with one quantifier
- 25 Multiple generality
- 26 Identity
- 27 Sentences of FOL
- 28 Definite descriptions
- 29 Ambiguity
- 30 Extensionality
- 31 Truth in FOL
- 32 Semantic concepts
- 33 Using interpretations
- 34 Reasoning about interpretations
- 35 Properties of relations
- 36 Basic rules for FOL
- 37 Proofs with quantifiers
- 38 Conversion of quantifiers
- 39 Rules for identity
- 40 Derived rules
- 41 Proofs and semantics
- 42 Introducing modal logic
- 43 Natural deduction for ML
- 44 Semantics for ML
- 45 Normal forms
- 46 Functional completeness
- 47 Proving equivalences
- 48 Soundness
- A Symbolic notation
- B Alternative proof systems
- C Quick reference
- 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.
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 policyLogical 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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