The Integral Cohomology of Toric Manifolds

We prove that the integral cohomology of a smooth, not necessarily compact, toric variety $X_\Sigma$ is determined by the Stanley–Reisner ring of $\Sigma$. This follows from a formality result for singular cochains on the Borel construction of $X_\Sigma$. As a onsequence, we show that the cycle map from Chow groups to Borel–Moore homology is split injective.