Cascade and Triangular source coding with causal side information

We consider cascade and triangular source coding with side information and causal reconstruction at the end node. When the side information at the source and intermediate nodes are the same, we characterize the rate distortion regions for both the cascade and triangular source coding problems. For the general cascade setting with causal reconstruction at the end node, we characterize the rate region when the sources satisfy a positivity condition, or when a Markov chain holds.