New posts in natural-deduction

Logic puzzle inspired by “Blue Eyes”

logic puzzle natural-deduction

What is the so-called eigenvariable or parameter in natural deduction?

logic first-order-logic quantifiers proof-theory natural-deduction

Prove if a = b, then f(a) = f(b) for any function f (with natural deduction)

functions first-order-logic natural-deduction

prove $( \lnot \lnot p \Rightarrow p) \Rightarrow (((p \Rightarrow q ) \Rightarrow p ) \Rightarrow p )$ with intuitionistic natural deduction

logic propositional-calculus natural-deduction

Does an inference rule under natural deduction operate on sequents or formulas?

logic proof-theory natural-deduction sequent-calculus

Natural Deduction Tautology

logic propositional-calculus natural-deduction formal-proofs

Main differences and relations between Sequent Calculus and Natural Deduction

logic proof-theory natural-deduction sequent-calculus

Restrictions on the use of universal generalization

logic predicate-logic first-order-logic natural-deduction

Need Hints Prove "$((\neg \alpha \to \alpha) \to \alpha) $" Using Axiom 1,2,3 and MP and deduction theorem

logic propositional-calculus natural-deduction

Difference between Logical Axioms and Rules of Inference

logic propositional-calculus axioms natural-deduction hilbert-calculus

Proving 'Law of Excluded Middle' in Fitch system

logic propositional-calculus natural-deduction

Motivation for natural deduction

logic soft-question natural-deduction formal-proofs

How is the implication introduction used here?

logic natural-deduction

Calculus of Natural Deduction That Works for Empty Structures

logic proof-theory formal-proofs natural-deduction formal-systems

Given ∃x.¬p(x), use the Fitch System to prove ¬∀x.p(x).

logic predicate-logic first-order-logic natural-deduction formal-proofs

Proof of double negation elimination using natural deduction

logic natural-deduction

Propositional Logic - Can you Derive $C \to A$ from $A$ alone, given the introduction rule?

logic intuition propositional-calculus natural-deduction

**Ended Competition:** What is the shortest proof of $\exists x \forall y (D(x) \to D(y)) $?

logic first-order-logic predicate-logic alternative-proof natural-deduction

natural deduction: introduction of universal quantifier and elimination of existential quantifier explained

logic proof-theory formal-proofs natural-deduction formal-systems

"Modus moron" rule of inference?

propositional-calculus natural-deduction