Elementary Equivalence in Logic and Mathematics
Elementary equivalence signifies that two structures share all the same first-order sentences.…
Effectively Decidable Theory
An effectively decidable theory is a formal system where an algorithm can…
Effectively Decidable Relations
An effectively decidable relation is one where a mechanical method can definitively…
Effectively Computable Functions
An effectively computable function is one that can be calculated by an…
Dynamic Modal Logic
Dynamic modal logic explores necessary and possible connections between events. It extends…
Dual of a Truth-Table and Formulas
The dual of a truth-table involves swapping truth values. Connectives like conjunction…
Doxastic Modal Logic: The Logic of Belief
Doxastic modal logic explores the reasoning behind beliefs. It models how rational…
Downward Löwenheim–Skolem Theorem
The downward Löwenheim–Skolem theorem states that if a theory has an infinite…
Double Turnstile Symbol (⊨) in Logic
The double turnstile (⊨) symbol signifies semantic entailment or logical consequence. It…