Steenrod coalgebras III. The fundamental group
  In this note, we extend earlier work by showing that if $X$ and $Y$ are delta-complexes (i.e. simplicial sets without degeneracy operators), a morphism $g:N(X)\to N(Y)$ of Steenrod coalgebras (normalized chain-complexes equipped with extra structure) induces one of 2-skeleta $\hat{g}:X_{2}\to Y_{2}$, inducing a homomorphism $\pi_{1}(\hat{g}):\pi_{1}(X)\to\pi_{1}(Y)$ that is an isomorphism if $g$ is an isomorphism. This implies a corresponding conclusion for a morphism $g:C(X)\to C(Y)$ of Steenrod coalgebras on unnormalized chain-complexes of simplicial sets. 
Justin R. Smith
math.AT