Bogoliubov-Parasyuk theorem

== English == === Etymology === Proved by Nikolay Bogoliubov and Ostap Parasyuk in 1955. === Proper noun === the Bogoliubov-Parasyuk theorem (physics) A theorem in quantum field theory, stating that renormalized Green's functions and matrix elements of the scattering matrix (S-matrix) are free of ultraviolet divergencies.