AA-infinity structure on Ext-algebras

Let AA be a connected graded algebra and let EE denote its Ext-algebra ⨁iExtAi(kA,kA). There is a natural A∞A∞-structure on EE, and we prove that this structure is mainly determined by the relations of AA. In particular, the coefficients of the A∞A∞-products mnmn restricted to the tensor powers of ExtA1(kA,kA) give the coefficients of the relations of AA. We also relate the mnmn’s to Massey products.