New posts in definition

What is the formal definition of polynomial ring of several variables?

Why is the arbitrary sum, but not the arbitrary intersection, of ideals an ideal?

What does it mean for a function to be holomorphic?

What is finitistic reasoning?

Why do we use open intervals in most proofs and definitions?

The first snippet below compiles, but the second doesn't. Why?

What is an interval of a lattice?

What is "algebra" in $\sigma$-algebra (or "field" in $\sigma$-field)?

Determine all homomorphic images of $D_4$ up to isomorphism.

Does this theorem/collection of theorems have a name? Or is it just seen as obvious?

What does "dual statement" mean exactly in category theory?

Two definitions for derivative

Meaning of $\int_E {f(x) \mu(dx)}?$

If a set is open, does it mean that every point is an interior point? [duplicate]

What is "one over something"?

What is the difference between an axiom and a definition?

Why is it difficult to define n-category?

Definition of a set

Question about the definition of a category

Graphically Organizing the Interrelationships of Basic Algebraic Structures