New posts in first-order-logic

Interesting examples of first-order, one-sorted proper extensions of PA

logic first-order-logic axioms natural-numbers peano-axioms

**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

Find the mistake of the reasoning

logic solution-verification propositional-calculus first-order-logic

topologic view on FO

general-topology logic algebraic-topology first-order-logic

First order logic: if A sentence is satisfiable then it is satisfiable in the natural number + even function

logic first-order-logic model-theory natural-numbers satisfiability

What an implication means when stating the solutions of an equation?

discrete-mathematics logic propositional-calculus first-order-logic predicate-logic

Axiom of Choice: What exactly is a choice, and when and why is it needed?

logic set-theory axiom-of-choice first-order-logic

Can a cyclic group be definined in 1st order logic?

first-order-logic

Cardinality of a language $L_\Sigma$ over a decidable signature $\Sigma$

first-order-logic model-theory cardinals formal-languages

How do we know what natural numbers are?

logic set-theory first-order-logic philosophy

Is there a 0-1 law for the theory of groups?

group-theory logic finite-groups model-theory first-order-logic

Why is Q → P a logical consequence of ¬(P → Q )

logic first-order-logic proof-theory