Let $M$ be a compact Riemannian manifold without a boundary. I wonder how the trace map $T:H^1(M \times [0,T]) \to H^{\frac 12}(M \times \{0,T\})$ is exactly.. can I split it into two trace maps for $M \times \{0\}$ and $M \times \{T\}$, and presumably these are bounded between the right spaces?
Can someone give me the rigourous details or give me a text?