Structure

Implication details

Claim: If a category has countable products and has ℵ₁-cofiltered limits, then it has products.

Proof: The product ∏i∈IXi\prod_{i \in I} X_i is the ℵ1\aleph_1-cofiltered limit of the countable partial products ∏i∈CXi\prod_{i \in C} X_i where CC ranges over the countable subsets of II.

This implication has a dual.

Show 10 categories using this implication