Consider a closed surface Sigma obtained by pasting two surfaces Sigma
(1) and Sigma(2) along some of their boundary components. A formula is
derived expressing quantum Yang-Mills functional integrals for Sigma
in terms of the corresponding integrals for the surfaces Sigma(i). Usi
ng this, a formula is derived which expresses the symplectic volume me
asure on the moduli space of nat SU(2) connections over a closed Riema
nn surface Sigma in terms of the corresponding volume measures for the
surfaces Sigma(1) and Sigma(2),when the latter have one boundary comp
onent each. (C) 1998 Academic Press.