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tamnd's digital brain — notes, problems, research
42810 notes
Axiom of Choice, equivalent formulations, constructible universe, consistency results, and independence phenomena.
The axioms of Zermelo Fraenkel set theory, the role of choice, and the use of axioms as a foundation for mathematics.
Cardinality, finite and infinite sets, countable sets, uncountable sets, and Cantor diagonal arguments.
Well ordered sets, order isomorphisms, ordinals, successor ordinals, limit ordinals, and transfinite induction.
Basic set theoretic language, including sets, membership, subsets, operations, relations, equivalence relations, order relations, and functions.
Cardinal addition, multiplication, exponentiation, finite and infinite cardinal arithmetic, and basic comparison laws.
Basic set theoretic notions including sets, relations, functions, cardinality, ordinals, well ordering, cardinal arithmetic, and the ZF and ZFC axioms.
Saturated models, realization of types, and their role in controlling definability and extensions.
Definition of definable sets and functions in first order structures, with parameters, examples, closure properties, and proofs.
Definition of complete and partial types, realization of types in structures, examples, consistency, and basic properties.
Detailed introduction to stability theory, counting types, order property, definability of types, and structural consequences.
Detailed overview of classification theory, dividing lines such as stability, simplicity, and NIP, and the structural analysis of first order theories.
Definable sets, definable functions, types, realizations, saturated models, stability theory, and classification programs.
Downward and upward Lowenheim Skolem theorems and their consequences for model sizes in first order logic.
Detailed development of the compactness theorem, its proof via completeness, and fundamental applications in model theory.
Expressive limitations of first order logic, including inexpressibility of finiteness and categoricity issues.
Applications of compactness and Lowenheim Skolem to algebraic structures and existence results.
Construction and properties of nonstandard models using compactness and Lowenheim Skolem.
Compactness, completeness, Lowenheim-Skolem theorems, nonstandard models, and limitations of first order logic.
Isomorphisms of first order structures, structural invariants, and properties preserved by isomorphism.
Examples of first order structures from algebra, order theory, graph theory, and geometry.
Basic model theoretic notions including languages, signatures, substructures, embeddings, elementary equivalence, isomorphism, and examples.
Elementary equivalence, theories of structures, and preservation of first order sentences.
Formal languages, signatures, and symbols used to describe structures in first order logic.
Substructures, generated substructures, homomorphisms, embeddings, and preservation of atomic formulas.
The cut rule, its elimination, and consequences for consistency and normalization.
Transformations of proofs, normalization, and structural properties of derivations.
Formal systems for deriving logical conclusions including natural deduction, sequent calculus, Hilbert systems, and proof transformations.
Introduction to natural deduction, inference rules, and structured proofs for propositional logic.
Sequents, structural rules, and introduction rules for logical connectives in the sequent calculus.
Hilbert style proof systems, axioms, and derivations using a minimal set of inference rules.
Validity, semantic entailment, satisfiability, countermodels, and logical consequence in first order logic.
Satisfaction, truth in a structure, models of sentences, and theories in first order logic.
Syntax of first order logic including terms, predicate symbols, and the formation of formulas.
Universal and existential quantifiers, scope, free variables, bound variables, and variable capture.
Structures, domains, and interpretations of symbols in first order logic.
Soundness, completeness, and the relationship between semantic validity and formal provability.
Conjunctive normal form, disjunctive normal form, and systematic conversion of propositional formulas.
Extension of propositional logic with terms, predicates, quantifiers, structures, satisfaction, models, validity, and entailment.
Logical equivalence, truth preserving transformations, and basic laws for rewriting propositional formulas.
Definition of propositional variables, logical connectives, and formation rules for well formed formulas.
Foundations of propositional logic including syntax, semantics, equivalence, normal forms, and proof systems.
Truth values, valuations, and evaluation of propositional formulas using truth tables.
How numbers move from concrete counting to abstract ideas.
Overview of mathematical logic, its scope, and the structure of the book.
Purpose, scope, and approach of this volume on the history and biography of mathematics.
How early humans developed counting, measurement, and basic mathematical thinking before formal notation.
Early counting through marks, objects, and physical recording systems.
Practical rules for writing mathematics in a clear, consistent, and readable way.
Common mistakes in mathematical writing and how to avoid them.
How to write mathematics with enough detail, few distractions, and clear logical structure.
How a mathematical paper or article is organized so that readers can follow the main ideas.
How definitions, theorems, and proofs work together in mathematical writing.
How to make computational results repeatable, checkable, and trustworthy.
Understanding the difference between manipulating exact mathematical expressions and computing with numerical values.
When to compute exact results and when to use approximations.
Overview of how to write mathematical ideas clearly, precisely, and in a useful structure.
How to think step by step and turn mathematical ideas into clear procedures.
Understanding how the cost of an algorithm grows with input size.
Overview of algorithmic thinking, computational methods, complexity, approximation, and verification in mathematics.
Using failures, boundary conditions, and extreme cases to test, refine, and understand mathematical statements.
Using structural similarity between problems to move ideas, methods, and proofs across domains.
Using examples, informal rules, and exploratory computation to guide mathematical problem solving.
Expanding or restricting a problem to reveal structure and guide solution.
Solving a problem by converting it into a simpler, known, or more structured form.
Using counting, random choice, and finite structure to prove identities and existence statements.
Overview of general methods used to approach, transform, and solve mathematical problems.
Proving a statement by starting from its assumptions and deriving its conclusion step by step.
Proving existence by giving explicit witnesses, algorithms, or methods of construction.
Using base cases and step rules to prove statements about objects built recursively.
Proving a statement by assuming its negation and deriving an impossibility.
Overview of the main methods used to prove mathematical statements.
Defining objects step by step and proving properties by following the same construction.
How transformations preserve structure and how invariants record what remains unchanged.
Breaking complex objects into simpler parts and building larger structures from controlled combinations.
How mathematics studies small pieces first and then assembles them into statements about the whole.
Understanding how reversing structure reveals parallel theories and results.
Overview of recurring patterns such as duality, symmetry, local-to-global reasoning, decomposition, recursion, and induction.
Understanding the benefits and costs of abstraction, and choosing the right level for mathematical work.
Studying mathematical systems themselves through languages, axioms, models, proofs, and interpretations.
Raising abstraction from objects and operations to maps, composition, and universal properties.
Working with explicit examples, calculations, and finite procedures as the base level of mathematical reasoning.
Replacing concrete values with symbols and rules to express general patterns.
Overview of how mathematics moves from concrete computation to structural and higher-level reasoning.
Concrete examples showing structural thinking across algebra, topology, and graph theory.
How preserved quantities and properties support comparison, classification, and structural reasoning.
Distinguishing abstract structures from their concrete instances, and using that distinction to reason across examples.
How isomorphism formalizes structural sameness and separates equality from equivalence.
Structure-preserving maps, their role in comparison, composition, and transport of mathematical information.
Viewing notation as a designed interface that exposes structure, supports composition, and enables efficient reasoning.
How formal precision and informal readability work together in mathematical writing.
How definitions introduce mathematical objects, fix meaning, and support reusable reasoning.
How mathematical writing balances exact statements with readable exposition.
How mathematical symbols and notation are chosen, scoped, reused, and designed for precision and readability.
Overview of structures, mappings, invariants, and classification in mathematics.
Overview of symbols, notation, definitions, and the balance between precision and readability.
How truth, provability, consistency, completeness, and independence appear across major branches of mathematics.
Overview of abstract objects, structures, equality, finiteness, and viewpoints in mathematics.
Syntax, axioms, inference rules, and the semantic interpretation of mathematical languages.
Core meta-properties of formal systems: avoiding contradiction and deciding statements.