proof theory

Derivation

Derivation is the process of establishing a result from a set of premises or axioms using logical rules. It's fundamental…

2 days ago

Weakening Rule in Logic

The weakening rule allows adding propositions to a logical derivation without invalidating it. This principle confirms that if a conclusion…

4 days ago

Weak Excluded Middle in Intuitionistic Logic

The weak excluded middle asserts that for any proposition P, either P or not-P is provable. This differs from classical…

4 days ago

Weak Counterexample in Intuitionistic Logic

A weak counterexample in intuitionistic logic signifies a lack of positive evidence for an instance of the law of excluded…

4 days ago

Weak Completeness in Logic

Weak completeness states that if a statement is semantically valid (true in all interpretations), then it is provable within the…

4 days ago

Understanding Logical Validity

Explore the concept of validity in logic, focusing on deductive arguments where true premises guarantee a true conclusion. Understand its…

4 days ago

The Turnstile Symbol (⊢) in Logic

The turnstile symbol (⊢) signifies syntactic entailment or provability in formal logic. It indicates that a statement on the right…

4 days ago

Tonk: The Fictional Logical Connective

Tonk is a fictional logical connective that highlights the necessity of inference rules in defining logical operators. It demonstrates how…

4 days ago

Syntactic Consequence in Formal Systems

Syntactic consequence defines the relationship between premises and conclusions derived through logical rules and axioms within a formal system. It…

4 days ago

Substructural Logic

Substructural logics are non-classical systems that alter or remove structural rules of classical logic, like relevance and linear logic, impacting…

4 days ago