Show that homology groups Hnℓf(X;G) can be defined using locally finite chains, which are formal sums ∑σgσσ of singular simplices σ:Δn→X with coefficients gσ∈G, such that each x∈X has a neighborhood meeting the images of only finitely many σ's with gσ=0. Develop this version of homology far enough to show that for a finite-dimensional locally compact CW complex X, Hnℓf(X;G) can be computed using infinite cellular chains ∑αgαeαn.