Quantum-field-theory application of L0 adjunction and monad. Connes & Kreimer 1998–2000: the combinatorics of BPHZ renormalization is encoded in a graded commutative Hopf algebra H of 1PI Feynman graphs with co-product Δ(Γ) = Σ_{γ⊆Γ} γ ⊗…
Quantum-field-theory application of L0 adjunction and monad. Connes & Kreimer 1998–2000: the combinatorics of BPHZ renormalization is encoded in a graded commutative Hopf algebra H of 1PI Feynman graphs with co-product Δ(Γ) = Σ_{γ⊆Γ} γ ⊗…