Upward Löwenheim–Skolem Theorem
The upward Löwenheim–Skolem theorem states that if a first-order theory has an…
Löwenheim–Skolem Theorem
A fundamental theorem in mathematical logic stating that any countable theory with…
Downward Löwenheim–Skolem Theorem
The downward Löwenheim–Skolem theorem states that if a theory has an infinite…
Denumerable Sets: Understanding Countable Infinity
A denumerable set is one whose elements can be matched one-to-one with…