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Mathematics
Mathematical Logic
1. Introduction to Mathematical Logic
2. Propositional Logic
3. First-Order Logic
4. Model Theory
5. Computability Theory
6. Incompleteness Theorems
7. Axiomatic Set Theory
8. Proof Theory
9. Modal Logic
10. Intuitionistic Logic
11. Higher-Order Logic
First-Order Logic
Limitations of Propositional Logic
Expressive Limitations
Need for Quantification and Relations
Examples Requiring First-Order Logic
Syntax of First-Order Logic
Language Components
Variables
Constant Symbols
Function Symbols
Predicate Symbols
Logical Symbols
Terms and Formulas
Construction of Terms
Atomic Formulas
Formation Rules for Formulas
Quantifiers
Universal Quantifier
Existential Quantifier
Nested Quantifiers
Quantifier Scope
Free and Bound Variables
Identifying Free and Bound Variables
Substitution Rules
Variable Capture
Alpha-Conversion
Sentences
Definition and Importance
Open vs. Closed Formulas
Semantics of First-Order Logic
Structures and Interpretations
Domain of Discourse
Interpretation of Constant Symbols
Interpretation of Function Symbols
Interpretation of Predicate Symbols
Satisfaction and Truth in a Model
Assignment Functions
Satisfaction Relation
Tarski's Definition of Truth
Models of a Set of Sentences
Definition of a Model
Finite vs. Infinite Models
Logical Validity and Consequence
Validity in First-Order Logic
Semantic Consequence
Logical Equivalence
Proof Systems for First-Order Logic
Extending Axiomatic Systems
Additional Axioms for Quantifiers
Universal Instantiation
Existential Generalization
Rules for Quantifier Manipulation
Extending Natural Deduction
Rules for Universal Quantifier
Rules for Existential Quantifier
Proof Strategies
Working with Assumptions
Extending Sequent Calculus
Quantifier Rules in Sequents
Eigenvariable Conditions
Cut-Elimination in First-Order Logic
Metatheory of First-Order Logic
Gödel's Completeness Theorem
Statement and Significance
Outline of Proof
Henkin's Proof Method
Compactness Theorem for First-Order Logic
Statement and Applications
Proof via Completeness
Löwenheim-Skolem Theorems
Downward Löwenheim-Skolem
Upward Löwenheim-Skolem
Implications for Model Theory
Skolem Paradox
Undecidability of First-Order Logic
Church's Theorem
Statement and Consequences
Reduction from Halting Problem
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2. Propositional Logic
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4. Model Theory