  The goal of this paper is to construct a semifree resolution for a
non-negatively graded strongly commutative DG algebra $B$ over the enveloping
DG algebra $B\otimes_AB$, where $A\subseteq B$ is a DG subalgebra and $B$ is
semifree over $A$. Our construction of such a semifree resolution uses the
notions of reduced bar resolution and tensor algebra of the shift of the
diagonal ideal.
