Introduction to CoproductsIntroduces coproducts in category theory, exploring their properties, universality, and relationships with products.
Direct Sums: Lemme 1.2Delves into direct sums of abelian groups, showcasing their coproduct properties and universal verification.
Homotopy LiftingExplains homotopy lifting, paths, proofs, constant paths, discrete spaces, and monomorphisms.
Triangular IdentitiesCovers triangular identities, natural transformations, commutative diagrams, and adjunction notation in group and category theory.